AFOSR Scientific Report

AFOSR 68-1625

NATIONAL BUREAU OF STANDARDS REPORT

9803

PRELIMINARY REPORT

ON THE THERMODYNAMIC PROPERTIES OF

SELECTED LIGHT-ELEMENT AND

SOME RELATED COMPOUNDS

(The previous semiannual reports in this series have the NBS Report

Nos. 6297, 6484, 6645, 6928, 7093, 7192, 7437, 7587, 7796, 8033,

8186, 8504, 8628, 8919, 9028, 9389, 9500, and 9601.)

<NB^>

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

This document is subject to special export controls and each

transmittal to foreign governments or to foreign nationals may

be made only with prior approval of the AFOSR (SRGL).
Qualified requestors may obtain additional copies from

the Defense Documentation Center.

NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards1 was established by an act of Congress March 3,

1901. Today, in addition to serving as the Nation’s central measurement laboratory,

the Bureau is a principal focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. To this end the Bureau conducts research and

provides central national services in three broad program areas and provides central national services in a fourth. These are: (1) basic measurements and standards,

(2) materials measurements and standards, (3) technological measurements and

standards, and (4) transfer of technology.

The Bureau comprises the Institute for Basic Standards, the Institute for Materials

Research, the Institute for Applied Technology, and the Center for Radiation Research.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the

United States of a complete and consistent system of physical measurement, coor- dinates that system with the measurement systems of other nations, and furnishes

essential services leading to accurate and uniform physical measurements throughout

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of an Office of Standard Reference Data and a group of divisions organized by the

following areas of science and engineering

Applied Mathematics—Electricity—Metrology—Mechanics—Heat—Atomic Physics—Cryogenics2—Radio Physics2—Radio Engineering2—Astrophysics2—Time

and Frequency.2 THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to methods, standards of measurement, and data needed by industry, commerce,

educational institutions, and government. The Institute also provides advisory and

research services to other government agencies. The Institute consists of an Office of

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Analytical Chemistry—Polymers—Metallurgy — Inorganic Materials — Physical

Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides for the creation of appropriate opportunities for the use and application of technology within the Federal Government and within the civilian sector of American industry. The primary functions

of the Institute may be broadly classified as programs relating to technological measurements and standards and techniques for the transfer of technology. The Institute

consists of a Clearinghouse for Scientific and Technical Information,3 a Center for

Computer Sciences and Technology, and a group of technical divisions and offices

organized by the following fields of technology:

Building Research—Electronic Instrumentation — Technical Analysis — Product

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1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted ; mailing address Washington, D. C. 20234.

2 Located at Boulder, Colorado 80302.

3 Located at 5285 Port Royal Road, Springfield, Virginia 22151.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

221-0404

221-0405

221-

0426

222-

0423

223-

0426

223-0513

313-0430

1 January 1968

PRELIMINARY REPORT

9803

ON THE THERMODYNAMIC PROPERTIES OF

SELECTED LIGHT-ELEMENT AND

SOME RELATED COMPOUNDS

(The previous semiannual reports in this series have the NBS Report

Nos. 6297, 6484, 6645, 6928, 7093, 7 192, 7437, 7587, 7796, 8033,

8186, 8504, 8628, 8919, 9028, 9389, 9500, and 9601.)

T echnical Summary Report

on the Thermodynamic Properties

of Light-Element Compounds

Reference: U. S. Air Force, Office of Scientific Research,

Order No. ISSA 67-6

IMPORTANT NOTICE NATIONAL BUREAU OF S

for use within the Government

and review. For this reason, t whole or in part, is not auth> Bureau of Standards, Washing

the Report has been speciticall

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

ess accounting documents intended

s subjected to additional evaluation

e listing of this Report, either in he Office of the Director, Nationa! by the Government agency for which

copies for its own use. <NB£p>

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

ABSTRACT

Thermodynamic and related properties of substances important

in current high-temperature research and development activities

are being investigated under contract with the U. S. Air Force

Office of Scientific Research (USAF Order No. ISSA 67-6) and the

Advanced Research Projects Agency (ARPA Order No. 20). This

research program is a direct contribution to the Interagency

Chemical Rocket Propulsion Group (Working Group on Thermochemistry)

and, simultaneously, to other organizations oriented toward

acquiring the basic information needed to solve not only the

technical problems in propulsion but also those associated with

ballistics, reentry, and high-strength high-temperature materials.

For given substances this needed basic information comprises an

ensemble of closely related properties being determined by an

extensive array of techniques. Some of these techniques, by

relating thermodynamic properties to molecular or crystal structure,

make it possible to tabulate these properties over far wider ranges

of temperature and pressure than those actually employed in the

basic investigations.

This report presents the results and interpretation of five

recent NBS experimental studies of thermodynamic properties, two

reviews which refine data treatment and evaluation, and one new

critical assessment of published heats of formation. The heat

capacity of beryllium nitride, Be3N2, was precisely measured from

0 to 315 K; after judicious correction for the irreducible

impurities, the data led to the common thermodynamic properties

from 0 to 315 K, complementing earlier NBS measurements from 273 to

1173 K. Precise high-temperature calorimetry gave the heat capacity

of tungsten from 1100 to 2600 K (showing no detectable difference

between two samples, one triple -zone -refined and 99 * 999% pure);

finally corrected results are given also for solid and liquid

beryllium aluminate, BeA^O^, from 1200 to 2 J4.OO K. A massspec trome trie investigation of A^2^3 containing 5 * 8% BeO identified

the high-temperature gas species and gave values for their standard

i
heats of formation. As part of the current NBS microwave and

infrared investigation of the alkali -hydroxide molecules, the

high-temperature microwave spectra of four isotopic varieties

of RbOH were observed and analyzed to give their molecular

constants; like CsOH (studied earlier ), RbOH is linear, with a low-frequency bending vibration of large amplitude. Two reviews

deal with reaction calorimetry involving fluorine compounds:

One documents the inadequacy of estimation rules for unmeasured

inorganic fluorides, and recommends a systematic cataloging

of results to achieve better consistency; while the other describes a new computer subroutine for the automatic reduction

of bomb-calorimetry data on organic fluorine compounds. As the

result of an up-to-date critical evaluation of the published

data giving AHf^g, AGf^g? an(* ^298 mgnes ium compounds,

values are documented and tabulated for 60 species of interest

in "light-element” applications

.

Thomas B. Doug/Las

Project Leader

iy_

Charles W. Beckett

Assistant Division Chief for Thermodynamics

Heat Division, Institute for Basic Standards

ii
TABLE OF CONTENTS

Page

Abstract i

Chap. 1. THE THERMOCHEMISTRY OF INORGANIC

FLUORINE COMPOUNDS. THE NEED FOR A

CATALOG OF THERMOCHEMICAL PROCESSES

(by George T. Armstrong) ! ! . 1. Estimates of Heats of Formation . Table 1. Accuracy of Estimates of

Heats of Formation of Some

Fluorine Compounds

2. Some Sources of Experimental Difficulty in

Measurements ... Table 2. Successive Determinations,

A Hf [^203 ( 0 ,0 )] . 3. Cataloging the Calorimetric Processes

References to the General Text . Table 3« Thermochemical Studies

Involving Tetrafluorome thane

Notes to Table 3 . . References to Table 3 • Table b» Process for AHf[CHj,(g)]

from Reactions of Table 3 • Fig. 1. Recent information on

the heat of formation of

aqueous hydrofluoric acid •

Chap . 2 . HEAT CAPACITY AND THERMODYNAMIC PROPERTIES

OF BERYLLIUM NITRIDE, Be 3N2 , FROM 20 TO 315K

(by George T. Furukawa and Fkrtin L. Reilly).

Abstract

I. Introduction

II. Apparatus and Method

Ill . Sample

IV. Results

V. References . Table 1. Summary of Spectroc hemic al

Analysis of the Sample of

Beryllium Nitride, Be3N2

Table 2 . Chemical Analysis of the

Sample of Beryllium

Nitride, Be^N2

Table 3 • Thermodynamic Functions for

Beryllium Nitride

^

3

^ ) .

1

1

2

3

3

6

9

11

12

15

16

17

19

19

19

19

20

23

25

27

28

29

iii
TABLE OF CONTENTS (Continued)

Fig. 1. Percentage Deviation of

the Empty Sample Vessel

Heat Capacities • Fig. 2. Percentage Deviation of the

Beryllium Nitride Sample

Heat Capacities . Fig. 3* Percentage Deviation of the

Beryllium Nitride Sample

Heat Capacities . Fig. H. Percentage Deviation of the

Initial Measurements from

the Beryllium Nitride Sample

Heat Capacities .

Page

30

31

32

33

Chap. 3* AUTOMATIC DATA REDUCTION APPLIED TO BOMB

CALORIMETRY OF ORGANIC FLUORINE COMPOUNDS

(by George T. Armstrong) T i ! T

Abstract . 1. Introduction

2 . New variables in the program . Table 1. Table of Thermochemical

Variables Expanded for

FARMST Subroutine

3. Subroutine FARMST

i|. Modifications to the main program

and subroutines

5 • Debugging

6 . Input Data Cards ......

Table 2 . 7. Output Data

Table 3 • References

3h

3h

35

36

38

51

52

5h

55

56

59

60

62

Chap. U. STRUCTURE OF THE ALKALI HYDROXIDES. III . MICROWAVE SPECTRUM OF GASEOUS RbOH

(by David R. Lide, Jr., and Chi Matsumura ) 63

Table I. Observed frequencies in

85RbOH and 85RbOD ... 6h

Table II . Observed frequencies in

S^RbOH and °'RbOD ... 66

iv
TABLE OF CONTENTS (Continued)

Table III.

Table IV.

Table V.

Table VI.

Table VII.

Effective rotational

constants and nuclear

quadrupole coupling

constants for various

vibrational states of

RbOH and RbOD . A -Doubling constants

Fit of BOv2^0 to

power series

Variation of rotational

constants with V-j_ . Structural parameters of

rubidium hydroxide

Chap . 5 • MASS SPECTROMETRIC STUDY AT HIGH TEMPERATURES

OF THE A£2 03-Be0 SYSTEM

(by J. Efimenko) ", Introduction

Experimental

Re suits

Discussion

Table 1. Ion Intensities Over

Eutectic BeO :AA2 03 ( 914.. 2$

A-&2 °3 )•••••

Table 2 . Auxiliary Data

Table 3* Equilibria Constants

Table U. Reaction Enthalpies .

Chap. 6. THE ENTHALPY OF TUNGSTEN FROM 1100 to 2600°K

(by E. D. West and S. ishihara )

", ! T

Ifethod and Apparatus

ly&terials

Re suits .........

Discussion

References

Table 1. Experimental Data for

the Enthalpy of Tungsten

Chap. 7. THE ENTHALPY OF SOLID AND LIQUID BeO*A42 02

FROM 1200° TO 2 U00°K- -REVISION

*

7by S. Ishihara and E. D. West)

67

68

69

70

71

72

72

72

72

73

75

77

78

79

80

80

81

82

83

8U

85

88

v
Chap. 8

TABLE OF CONTENTS (Continued)

THE STATUS OF THE THERMOCHEMICAL DATA

ON SOME Mg COMPOUNDS

(by Vivian B. Parker)

I. Introduction

II. Discussion of Data .... Mg(c), Mg(g) .... Mgn+

(g), Mg2 + (aq), MgO(macrocr .

)

MgO(microcr .

)

MgO(g)

Mg%(c), MgOH+ (aq), Mg(OH)2 (c)

Mg (OH )p (ppt ) , Mg(OH)2 (aq), Mg(OH)2 (g

MgF(g)

MgF2 (c), FfeF2 (g)

Table I

MgC^(g), MgCi2 (o)

Mg«2 (g) . . MgCi2 (aq), MgCVHgOCc),

MgM2 ‘2H2 0(o )

Table II

MgM2 'UH2 0(c ) MgCi2 -6H2 0(c), Mg(C^OK)2 (e),

Mg (C^O[| ) 2 (aq ) , Mg(aOh ) 2 *6%0{c ) MgOHCA(c), MgBr 2 (c), MgBr2 (g)

MgBr2 (aq) MgBr2 '6HpO(c ), Mgl^(c),

Mgl2 (g), Mgl2

(aq')

Mgl2 (aq), MgSOr (c ), MgSOj

| (aq)

MgSO^-HpOO: ), MgS(X *f^O(amorph),

MgSq4 -2H2 0(c), MgSOh* 14.1^0(0 ),

MgSOT -6^0(0)

MgSOK’7HoO(c), Mg3N2

(c ,a ). Mg(N03 ) 2 (o)

Mg(N03

) 2 (aq), Mg(N03) 2 -21^0(0 ),

]yfetN03

) 2 -6^0(0) . MgC2 (o), Mg2 C

3tc ), MgC03

(o) . Mg2 Si(c), MgSi03 (c), Mg2 S10L (c ) Mg 3Si2 0

5

(OH)j, (cl, Mg3SiU

(>LOtOH)2

(c ),

MgBi2 (c), MgA^2

0)4

'(c ). Mg2A^Si3

Ol8 (c ) .... Bibliography

Table III. Selected Values

for Some Mg

Compounds at 298°K

,

Page

90

90

90

90

91

92

93

9h

95

96

96

97

98

99

99

100

101

102

103

10l|

105

106

107

108

109

no

111

112

120

vi
Chapter 1

THE THERMOCHEMISTRY OF INORGANIC FLUORINE COMPOUNDS

THE NEED FOR A CATALOG OF THERMOCHEMICAL PROCESSES

1

George T. Armstrong

Heat Division, Institute for Basic Standards

National Bureau of Standards, Washington, D. C., 2023U

1. ESTIMATES OF HEATS OF FORMATION

Some years ago we reviewed (see for example [1]) the effectiveness of

estimates of the heats of formation of inorganic fluorine compounds by a procedure which we have not seen used elsewhere. We compared estimates of

heats of formation for which no measured value existed at the time of the

estimate, with later values measured experimentally. The estimates were,

thus, a priori in a sense. By this tactic we hoped to avoid the possibility

of (no doubt unpremeditated) influence of the measured value upon the quality

of the estimate. We considered, for instance, that if a measured value were available the author of an estimate might be influenced favorably in

his decision to publish by good agreement of his estimate; or, contrariwise,

unfavorably and decide not to publish if agreement were poor; thus we would

anticipate that estimates made after the availability of experimental data

might tend to be better than estimates made prior to such availability.

Some new information has been added and the comparisons are shown in

Table 1. The average error (without regard to sign) is kb kcal mol 1

, and

the average bias is 26 kcal mol 1 positive, as compared with our earlier

finding of 30 and 17 kcal mol

1

, respectively. Thus, the ability to

estimate heats of formation was not particularly good, and recent data

have continued to show large deviations. The tendency is for the compounds

of fluorine to be more stable than estimated.

The difficulty may be due in part to the extreme position of fluorine

in the periodic system, which causes all attempts to estimate on the basis

of the properties of neighboring elements to be extrapolations rather than

interpolations

.

1

Prepared for presentation at the Thermodynamic Symposium of the IUPAC Commission

on Thermodynamics and Thermochemistry, Heidelberg, West Germany, September 1967*

1
Table 1

Accuracy of Estimates of Heats of Formation of Some Fluorine Compounds

Compound AH^

-1

kcal mol Error

Estimate Later Measurement

AcF^ (c ) -1|20 -477 +57

-395 +82

AAF

3

(c) -311 -361.0 +50

-323 +38

AuF

3

(c ) -100 - S3 .3 -17

BeF

2

(c ) -227 -21*5.3 +18

-220 1A +CVJ HfF^(c) -435 -1*61 . 1* +26

MoF

6

(A) -405 -388.6 -16

NF

2 (g) 17 8.9 + 8

NbF-(c) -342 -1*32 +90

H*(k) -315 -381. 1* +66

—ij.20 -39

RuF^(c) -300 -213 . 1* -87

SF

u

(g) -156 -171.7 +16

TaF^(o) -300 -1*55 +155

-360 +95

ThF^Co) -477 -1*82 + 5

TiF^(c

)

-370 -3?1*.2 +2U

TXF(c ) - 65 - 74.0 + 9

WF- (c

)

-175 -136.9 -38

ZrF^(c) -1*45 -456.8 +12

Average error UU kcal mol

Average bias 26 kcal mol

Estimates are selected from a review by Armstrong and Krieger [2]«

2
We have not made a general study of the problem of predictions of binding energies or of the relative effectiveness of the different methods that

have been used. This is a worthwhile exercise, and possibly if we had done

so we would have somewhat less of a blunderbuss approach to the results.

However, our concerns up to now at least have been primarily in other

directions. The information which has been presented to you was enough to

persuade us to adopt a skeptical attitude toward estimates. It is apparent

that competent and well established reviewers have on the whole shown a lack of ability to predict a priori with reasonable accuracy the heats of

formation of inorganic fluorine compounds.

2. SOKE SOURCES OF EXPERIMENTAL DIFFICULTY IN MEASUREMENTS

The unusual bias of predictions, together with a curious regularity

observed in successive experimental determinations of certain heats of

formation, led to the formulation of a rather general rule, that members

of cur laboratory have rather facetiously termed Armstrong's rule x as

time goes by heats of formation tend to become more negative. In the denouement we hold no brief for this rule, but point it out as an interesting

interlude in our examination of the findings of experimental thermochemistry.

An example that led to this attitude is the heat of formation of

aluminum oxide (Table 2 ) which became significantly more negative over a period of 30 years. The heat of formation of AlF^ has followed roughly

this rule, we see semblences of it also in the heats of formation of • BeO(c), BeF^Cc), CF^(g), and HF(aq).

Table 2 Successive Determinations AKf [Al^0^(c,o)]

Moose and Parr (1924) [3]

lccal mol ^

-376.9

Roth and Muller (1929) [4] -380.1

Snyder and Seitz (1945) [5] -399.09

Oketani and Maebashi (1950) [6] -381.03

Holley and Huber (1951) [7J -400.29

Schneider and Gattow (1954) [8] -400.6 (-402 y Mah (1957) [9] -400.4

The number in parenthesis included a questionable correction made by the

authors for partial formation of a less stable phase.

3
When we examine these tendencies in greater detail, however, we find,

perhaps not surprisingly, that the picture was oversiirplif ied. Still,

certain regularities of behavior do persist, and lead us to believe there

is sera? rational explanation of these regularities. The explanations which

finally appear to emerge are not the same in every case. That is, a variety

of influences is apparently at work. An examination of a few of them may

assist us in planning future experimental work.

We return to the heat of formation of AX 0o briefly and note that each

j

value quoted resulted from combustion of the metal in oxygen. With a little

imagination we realize that prooably the cause of progressively more

negative heats of formation was better control of the amount of reaction as time passed. The less negative values probably represent smaller amounts

of reaction than the experimenter presumed. There may be two reasons for

this bias: (l) the samples metal may have contained larger amounts of inert

impurities than were revealed by analysis; (2) the metal may have reacted

less completely than presumed. The first source of error is rendered

plausible by the finding of relatively large amounts of oxygen and nitrogen

(probably as a surface coating) in metals even supposedly highly pure on the basis of spectrographic analysis. The second source of error is

rendered plausible by the fact that the combustion product may completely

cover small amounts of unburned metal and preclude further oxidation. On

the basis of an argument like the above, we would anticipate in the

combustion of refractory substances giving solid products, a bias in the

direction of low heat of reaction which might be substantial in some cases. A notorious example of this is the combustion of boron in oxygen, for

which the two processes may both be presumed to be severe. Let us turn to

a more complicated and informative example, the heats of formation of

CF, and HF.

4

A few years ago, apparently valid but inconsistent experiments were

reported by Jessup [10] on the one hand and by Good, Scott and Waddington

[11] and by Neugebauer and Margrave [12] on the other hand, all of which

gave values for the heat of formation of CF^. See Table 3 • In an attempt

to reconcile them we observed the opposing sense in which the heat of

formation of HF occurred in the relationships between the heats of reaction

and the heat of formation of CF^. These relationships are shown in

Table U, referring to reactions 2, 3b, and 1+c. This led us to make the

h
suggestion that possibly the heat of formation used for HF in the calculation was in error, and it was no problem then to figure a reasonable

change in the heat of formation of HF that would reconcile these inconsistent sets of experiments*

In Table 3 we list all the reactions involving CF^ for which we have

found calorimetric studies.

If we restrict ourselves to the reactions from which the heat of forma

tion of CF^ is derived by its difference from HF (rather than from its sum

with HF) as in reactions 3(a,b,d), U(a,b,c), £(a,b,c) and possibly 8, and 9

we find a rather nice consistency between the calculated values for CF^

no matter what value is selected for HF(aq). An illustration of this is

given by Cox, Gundry, and Head [13], using an extreme value for the heat

of formation of HF(aq),

The heat of formation of CF^ as inferred from these experiments is

inextricably bound to the heat of formation of HF(aq). It is evident that

we shall not learn anything further about it from them alone, so long as

there in fluctuating information about the heat of formation of HF.

We may turn to the experiments that do not involve HF. Here we find

ourselves in reaction sets 1, 6, and possibly 8 and 9 , immediately faced

with the same problems or at least similar problems to that mentioned

earlier in the case of Far instance, in reactions (8) ani (9), involving

the reduction of an organic compound and the formation of a solid residue

carbon, the question arises, ”to what extent has this reaction gone to

completion?” Completion here includes two concepts: (l) has all of the F

been extricated from the C residue? and (2) has the C residue been reduced

to a recognizable, well defined standard state, or does it retain active

centers (as a result of a large surface area, for example)? The experimental evidence, particularly with respect to the latter problem, as outlined in the notes to Table 1 is dishearteningly unsatisfactory. One is

left with the feeling that the observed heat processes will tend to be

biased toward the low side of the true heat of reaction.

Only by the most careful experimentation can one be sure that the

observed heat actually corresponds to the expectation for a complete reaction described exactly by the equation.

5
Somewhat peripheral to our subject, the analysis of these equations

led us to an understanding x a) That the heat of formation of CF^ is best represented by the

experiments on direct combustion of graphite in fluorine; and

by a combination of the combustion of "Teflon” in oxygen and

in fluorine, the only products being gaseous CO^ and CF^.

(2) That other reactions not involving KF do not provide any conflicting evidence, but that the positive information they provide is

limited by the lack of characterization of the reaction

(3) That reactions involving HF(aq) do not provide conflicting

evidence, but that the positive Information they supply is

limited by uncertainty in the heat of formation of HF(aq).

(incidentally, tne reaction by Jessup et al„ [10] which was

an initiator of the line of thought described here, turns out

g

; 7 now to be inconsistent in the opposite sense from what it was

at the outset, and no means of reconciliation is now apparent* )•

(4) That the reactions involving HF(aq) can be combined with

«

:

:

: 3 : . Ods XIQZ -

' -----

independently arrived at values for heats of formation of CF^

as well as BF~ and KF1 ) to arrive at new "consensus” values for

the heat of formation of HF(aq). Figure 1 shows the apparently

most consistent value for heat of formation of HF(aq).

(5) That the explanation of the observed discrepancies in measurements

of the heat of formation of HF(g) or HF(aq) by various means may

involve subtle arguments. The large deviation of the work of Cox

* cp * n : 'hoc

and Harr op [19], for instance, may be due not to experimental

error but to a residual entropy of IdHFg, (c ) at absolute zero, or

to use of an inappropriate value for the heat of formation of

gaseous HF. In the latter event, the heat of formation of

gaseous HF is still a problem. .. . 3. CATALOGING THE CALORIMETRIC PROCESSES

A feature is present in Table 1 which, undoubtedly, is not new but

suggests to us what we believe is a new concept of the appropriate forms

•

• •

- • ' for presenting calorimetric (and other thermodynamic ) data.
We have no question in our mind that the most useful form of thermooyiuonic information for the general user — the theoretician interested

in energies of substances, and the engineer interested in design parameters —

i3 a set of tables of values of thermal functions of the substances in the

style of KBS Circular 5 00 [2 0] (now Technical Note 270-1) [21] or of the

JANAF Thermochemical Tables [22] from the U.5.A. or the Thermal Constants

of Substances [23] and Thermodynamic Properties of Individual Substances [2k]

from the Academy of Sciences of the USSR. However, for the thermochemist,

the experimental calorimetrist, or the selector of best values, another

form seems at least as desirable, and in the latter case almost a necessary

adjunct to his work. This form is a catalog of thermochemical processes.

We have seen in Section 2 that a set of equations together with the

heat values associated with them is a flexible tool for attempting to

determine true values of the heats of formation, and to appraise sources

of errors. It is also apparent that critical substances for further study

would be discernible in such a set of equations.

A catalog can be conceived of as a tabulation of observed processes —

chemical reactions, phase changes, and so on — listed as equations, with

the value of the thermal effect observed. Limited amounts of selected

information concerning the conditions of the experiment are also included.

The tabulation of equations is indexed with respect to all substances and

phases present, so that all processes involving a given substance can be

located.

The limited list of equations involving CF^ given in Table 3 represents a skeleton of a limited segment of such a catalog. To prepare a complete catalog including all the chemical substances for which measurements have been made is a very large task. In the following paragraphs

we indicate certain special features of such a compilation and suggest the

long term benefits which it might be expected to provide.

There is ample evidence that several groups now have essentially the

framework of such a catalog. These are the groups which have been for some years compiling and critically evaluating thermodynamic data. The awkward

feature of the present situation is that the information, except for the

end result after it has been critically evaluated and released in tables

of selected values, is essentially in the form of private files. In this

form it is inaccessible to the general investigator; in the event of the
formation of a new critical evaluation group, they must acquire their own

file of such working information; in the event of the demise of one of

these groups, its literature files would probably revert to inutility.

We suggest that much of the intermediate information gleaned from the

thermochemical literature is of permanent value, subject to reuse in

various way3, and susceptible to augmentation as time goes on without loss

of any of the original body of information. In this respect, particularly

it is more useful than a collection of selected values of thermodynamic

functions, whose values change as new data are added.

i A catalog in the form described can be looked upon as a set of

mathematical equations or expressions of which a selection is given in

Table h* In general, most of the thermodynamic relationships involving

heats of formation can be described as linear equations. The set of

possible chemical reactions involving all the chemical substances may be

looked upon as a set of simultaneous equations. Experimental enthalpy

changes can be expressed in terms of the numerical coefficients and heats

of formation of the substances present.

Because of the complexity and number of these equations, and the

difficulty of finding simultaneous solutions which offer the best values

of the heats of formation, the practice has been adopted of evaluating heats

of formation sequentially, starting with certain "key” substances, to which

values of heat of formation are assigned on the basis of carefully selected

equations.

In principle, if the experimental enthalpy equations are known for

any given set of substances, a set of best values can be selected which

minimizes the ensemble of errors without predetermining any one key substance. This minimization is ordinarily not done because of its difficulty.

It is to be presumed that the use of high speed computers will ultimately allow selections of best values in this sense for the whole body of

chemical substances for which data exist. A catalog of the type described

above is a critical development if such a calculation is to be achieved.

The catalog will essentially provide the input data for such a selection

of best values.

8
With a workable program for making such selections, it should be

I possible to make selected best values annually, or more frequently; it

should be possible to study the relative importances of various substances;

and also to find those substances whose present values appear to be out

of line and require redetermination.

Thus a catalog provides three services;

(1) A resource for experimental calorimetrists for planning their

work.

(2 ) Source material for groups preparing best values of thermodynamic

properties

.

(3) Input data for computerized selection of best values and other

computerized analysis of data.

References to the General Text

[1] G. T. Armstrong, J. Chem. Ed. IfL, 297-307 (1961; ).

[2] G. T. Armstrong and L. A. Krieger, in "Progress in International

Research on Thermodynamic and Transport Properties," J. F. Masi and

D. H. Tsai, Editors, (Academic Press, N. Y. 1962), pp. 8 -78 . [3] J. E. Koose and S. W. Parr, J. An. Chem. Soc. U6_, 2656-61 (192 U).

[ 4 ] W. A. Roth and D. Mailer, Z. Physik. Chem. (Leipzig), AlJfl;, 253-8, (192 9).

[5] P. E. Snyder and H. Seitz, J. Am. Chem. Soc. 67, 683-5 (19U5).

[ 6 ] S. Oketani and Y. Maebashi, J. Japan. Inst. Metals lI;B, No. 2, 27-31,

(1950).

[7] C. E. Holley, Jr. and E. J. Huber, Jr., J. Am. Chem. Soc. 22j £577-9,

(1551).

l 8 ] A. Schneider and G. Gattow, Z. Anirg. u. Allgem. Chem. 277

l£- 8 , (195U).

[9] A. D. Mah, J. Phys. Chem. 61, 1572-3 (1957)*

[10] R. S. Jessup, R. E. McCoskey, and R. A. Nelson, J. Am. Chem. Soc. £7,

2U;-5 (1955).

[11] W. D. Good, D. W. Scott, and G. Waddington, J. Phys. Chem. 60,

1080-9 (1956).

[12] C. A. Neugebauer and J. L. Hargrave, J. Phys. Chem. 60. 1318-21 (1956).

[13] J. D. Cox, H. A. Gundry, and A. J. Head, Trans. Faraday Soc. 60 , 653-65 (1961;).

[ll;] E. S. Lomalski and G. T. Armstrong, J. Res. Nat. Bur. Std. 71A (1967)

(in press).

9
[15] G. K. Johnson, H. M. Feder, and W. N. Hubbard, J. Phys. Chem. 22j

1-6 (1966).

[16] G. H. Sinke, J. Phys. Chem. 2i> 3$9 (1967)*

[17] E. S. Domalski and G. T. Armstrong, J. Has. Nat. Bur. Std 71A,

105-18 (1967).

[18] R. C. King and G. T. Armstrong, Unpublished data.

[19] J. D. Cox and D. Harrop, Trans. Faraday Soc. 61, 1328-37 (1965).

[20] F. D. Rossini, D. D. Wagman, W. H. Evaii3, S. Levine, and I. Jaffa,

"Selected Values of Chemical Thermodynamic Properties," Nat. Bur.

Std. (U.S.), Circ. 500, (U. S. Government Printing Office,

Washington, D. C., 1952, 1961).

[21] D. D. Wagman, W. H. Evans, I. Halow, V. B. Parker, S. M. Bailey, and

R. H. Schumm, National Bureau of Standards Technical Note 270-1,

(U.S. Government Printing Office, Washington, D. C., 1965).

[22] JANAF Thermochemical Tables, Dow Chemical Company, Midland, Michigan

(1960-67).

[23] V. ?. Glushko, et al.. Thermal Constants of Substances (Akad. Nauk

SSSR, Moskva 1965, 1966).

[2U] V. P. Glushko, et al. " Thermodynamic Properties of Individual

Substances (Akad. Nauk SSSR, Moskva 1962).

10
Table 3« Thermoc hemic al Studies Involving Tetrafluoromethane

0 "l Reaction ML Kcal mol References

.

1. C(o, graphite) + 2F

2 (g) “ CF^(g) -162 ±2

a

[1]

(-183 .5±2 )

b

[3]

-222.87±0.38 [6]

2. CH^(g) +iiF

2 (g) -

: .CFj

t (g) + l*HF(g) -1*59. 3±9 [7]

3(a) C„F, (g) = CF, (g) + C (c , graphite

)

Cm -6l.2*3±l.l* • [8]

(b) C

2

F

u

(g) + 21^ (g ) + 1*0.18.2^0] (X) = •

-65.1*±0.1*2 [9]

1*[HF+118.2H

2 0] (X ) + 2C(c, graphite) -150.8±1.1 [9]

(c) C

5F^(g)+2I^ (g) = l*HF(X)+2C(c, graphite)

(d) 1*[HF+118.2H

2 0] (X) + C(c, graphite) = -132.72±0.7 [8]

GF

1; (g)+2H

2 (g) + i*[ll8.2^0](X) +85.1* ±1.5

(e) 1*HF(X)+C(c,graphite) = CF^(g) + 2H2 (g) +67-32

l*(a) (solid polymer )+0

2 (g) = C02

(g )+CF^(g)

(b) C

2

Fi (solid polymer ) +0

2 (g) + 1*2I^0(X) = -118.8+0.5 [10,11]

2C0

2 (g)-d*[HF+10H

2

0](X) -160.3±0.9 [10,11]

(o) C0

2 (g)+U[HF+10^0](X) = CF

1+ (g)-fi*2H

2

0(X)

5(a) C

12

F

22

(X)*6.50

2

(g)+l;01.8l^0(X) = 0.6CF

1; (g) +

+1*1 .5 ±1.0 [10,11]

11.1* C0

2 (g) + 19.6[HF+20I^0](X)

(b) C

12

F

22 (X)^.502 (g)+131.2H2 0(X)-3.90I[

t (£) +

-1*067. 9A. 181* ' [12]

8.1C0

2 (g) + 6.2* [HF+2011,0] (X) -31*96 .5/1*. 181*

(o) C0

2 (g)+1*[HF+20H2

0](X) = CF

i+ (g)+82H

2 0(X) +1*1.38+0.32 [12]

6(a) C

2F^(solid polymer )+F

2 (g) = 2CF^(g) -2l*7.85(-2l*7J*3)±a30 [5,6]

-2l*6.81*±0.07 [17]

(b) C

2

F|

t (solid polymer )+Og(g) » C0

2 (gJ+CF^tg) -118.8 [10,11]

(o) C0

2 (g) + F2 (g) - 02 (g) + CF^(g) -129.05(128.63)

7. Hg, 0

2

, CO, CF^ -220.1±1.1* [13]

8- CFi (g)+2*K(c) = ItKF(c) + C (graphite) -307±i* [2,1*]

-320±2 [15]

9. CFi (g)+l*Na(c) « l*NaF(c)+C (graphite) -325.5±2.2 [16]

See separate set of references for Table 3*

11
Notes to Table 3

1* a* The original authors made an adjustment of 2.U kcal mol” for the

estimated heat of formation of the Norite (activated wood charcoal)

they burned# They obtained -165.0 ±1.5 kcal mol ^ for the combustion

of Norite in fluorine. When adjusted by +2.U kcal mol”^ this gives

-162.6 kcal mol”'

1' which they apparently rounded to -162 kcal mol”\

-1

increasing the uncertainty to 2 kcal mol • b. This is an adjustment by Ruff and. Bretschneider [3] of the work of

von Wartenberg and Schuette [1], taking into account the formation of

several percent of higher fluorocarbons in the combustion of Norite.

The recalculation changes the original data far too little. A recalculation using a more current value for the fluorination of a C-C

bond (1I4.2.7 kcal mol”^ instead of 107 kcal mol”*^ as was used by

Ruff and Bretschneider) leads to = -190.5 kcal mol”\ Hence it

appears that the formation of other products would have to be greater

than was suggested by Ruff and Bretschneider. The uncertainty in

amount of products seems to preclude further consideration of the work

of von Wartenberg and Schuette.

2. As a part of its uncertainty the work of Jessup, MsCoskey, and

Nelson [ 7 ] contains an uncertain correction of 1.5 to 2.0 kcal mol ^

(of CF^) for nonideality of HF. This now appears to have been an

excessive correction. In the extreme case, if this correction is re-

-1

duced to zero, the heat of reaction becomes -U6X.2 kcal mol • The

large uncertainty assigned by the authors is apparently a 95 percent

confidence limit.

3» a. The carbon formed in the reaction by Duus [8] was weakly crystalline. Duns made no adjustment to the heat for the physical state of

the graphite . An adjustment of the magnitude made by Neugebauer and

-1

Margrave [9] would bring Duus* value to -63*3 kcal mol • Neugebauer

and Margrave [9] measured the heat of reaction, with the formation

«1

amorphous carbon, to be -63*5 kcal mol , and measured the heat of

formation of the amorphous carbon to be 1.9 kcal mol”\ We have

combined their measurements to give the heat of decomposition to

—1

form graphite, -65 kcal mol •

12
b, c. Neugebauer and Margrave [9] measured the heat of hydrogenation

of C

2 F^(g), with the formation of HF(aq) and amorphous carbon, to be

—3JL1.7 • 8 kcal mol x

, and measured the heat of formation of the amorphous

-1

carbon to be 3*0 kcal mol • We have combined their measurements to

give the heat of hydrogenation to form HF(aq) and graphite,

AH ** -150.8 kcal mol"\ Their reaction is definitely superior to

reaction 3(c) as carried out by Duus, who was forced to make large

corrections for the presence of HF(g), and did not attempt any correction for the physical state of the carbon formed. Neither reaction

3(b) nor 3(c) can be used by themselves to calculate the heat of formation of CF^, but are included because they can be combined with other

work done in the same laboratory to obtain a relationship leading to

the desired value.

d. This reaction is obtained by subtracting 3(b) *from 3(a). The heat

value cited was obtained using the heat of reaction 3(a) determined by

Neugebauer and Margrave [9]. e. The heat of this reaction was determined by combining the energy

of reaction 3(c) with that for 3(a) determined by Duus [8] and

reported in the same paper.

U* a,b. The energies of these reactions were obtained by Good, et al. [10],

[11] by extrapolating respectively to x » 1 and x - 0 from measurements covering the range x « 0.02 65 to x = 0.8162 of the reactions

(solid polymer) + 0

2 (g) + 1*2 (1-x 5^0(1) * (2-x)C0

2 (g) +xCF^ +

lj.(l-x)[HF + lOHgO] (l). The experiments are carefully described.

c. The heat of this reaction was obtained by conbining the heats

of reactions l*(a) and l±(b) determined in the same laboratory.

5. a. The heat of this reaction was obtained by Cox, Gundry, and

Head [12] by appropriately combining reactions 5(a) and 5(b).

6. a. An earlier (in parentheses) and a more recent and more amply

substantiated value are listed.

b. The heat of this reaction is obtained by combining the heats of

reaction 6(a) and 4 (a). This reaction does not in any way involve

the heat of formation of HF, but in order for it to be valid, the

C

2

F^ (solid polymer) used in the two different experiments must be

similar.

13
Baibuz and Medvedev [11+] recalculated the work of Baibuz [13]

mid reported AHf [CF^(g)] “ -220.6. The work of Baibuz ia not available to us in sufficient detail to allow U3 to write the equation

for the reaction or to know the dependence of the reported heat of

formation of CF^ on other auxiliary data.

, Von Wartenberg [2,U] reported AH 3 -307 kcal mol"*

1*, and although

he indicated the carbon was graphite, the evidence .from other sources

is that probably only a slight amount of graphite was present. On the

basis of information supplied by Neugebauer and Margrave (1.5 to

1.9 kcal mol [9], von Wartenberg and Schuette (2.1; kcal mol”^*) [1],

and Kirkbride and Davidson (2.5 kcal mol [15] if we assume the heat

of formation of the carbon residue to be +2 ±1 kcal mol"*

1

* and apply

a correction, the heat of reaction to that in which graphite is formed

would be -307, which is still far less negative than the result of

Kirkbride and Davidson.

Kirkbride and Davidson [l5] reported AH^[GF^(g)j 3 -218 ±2

kcal mol"^, together with auxiliary data for XF(c) and amorphous

-1

carbon. We have back calculated to obtain AH 3 -320 ±2 kcal mol . Vorob *ev and Skuratov [16] reported AH^ « -325*5 ±2.2 kcal mol

and that their reaction led to formation of 3 -graphite. If we presume,

on the basis of the work of Kirkbride and Davidson [15], that only a

small amount of crystalline material was present and apply a correction

of 2 kcal mol"'

1

* for the heat of formation of amorphous carbon, the

-I heat of reaction 9 would be -327*5 kcal mol • See 8 above.
References to Table 3

[1] Wartenberg, H. v., and Schutte, R., Z. Anorg. Allgem. Chem. 211,

222-6 ( 1933 ).

[2] Wartenberg, H. von, Z. Anorg. Chem. 258, 356-60 (1949).

[3] Ruff, 0. and Bretschneider , 0., Z. Anorg. Allgem. Chem. 210,

173-83 (1933).

[4] Wartenberg, H. von, Nachr. Akad. Wiss. Goettingen, Math. Pbysik. Kl,

1946, 57.

[5] Domalski, E. S. and Armstrong, G. T., J. Res. Nat. Bur. Std. 6?Af 137-47 (1965).

[6] Domalski, E. S. and Armstrong, G. T., J. Res. Nat. Bur . Std. 71A t 105-118 (1967).

[7] Jessup, R. S., MeCoskey, R. E., and Nelson, R. A., J. Am. Chem.

Soc. X7, 244-5 (1955).

[8] Duus, H. C., Ihd. Eng. Chem. 41, 1445-9 (1955).

[9] Neugebauer, C. A. and Ifergrave, J. L., J. Phys. Chem. 60, 1318-21 (1956).

[10] Good, W. D., Scott, D. W., and Waddington, G., J. Phys. Chem. 60,

1080-9 (1956).

[11] Scott, D. W., Good, W. D., and Waddington, G., J. Am. Chem. Soc. Tit

2b5-6 0-955).

[12] Ccoc, J. D., Gundry, H. A., and Head, A. J., Trans. Faraday Soc. 60,

653-65 (19610.

[13] Baibuz, V. F., Boklady Akad. Nauk S.S.S.R. 140, 1358-<50 (1961).

[Hi] Baibuz, V. F. and Medvedev, V. A., Tr. Gos. Inst. Prikl. Khim.,

No. 49, 84 (1942).

[15] Kirkbride, F. W. , and Davidson, F. G., Nature 174. 79-80 (1954).

[16] Vorob ! ev, A. F., and Skuratov, S. M. , Zh. Fiz. Khim. J2_, 2580-5 (1958).

[17] Wood, J. L., Lagow, R. J., and Margrave, J. L. , J. Chem. Eng. Data,

1967. In press.

15
Table h

Process for AH^[CF^(g)] from Reactions of Table 3*

Reaction

1 A^d)

r\4 AH,, (2) + AH^CH^g)] - liAHetHF(g)]

3(a) • AHp(3a) + A%[C

2

F

li (g)]

3(b) AH (3a) - AH

r (3b) + 1|AH.[.[HF in 1X8.2 fLO] (A)

3(c) AH, (3a) - AH

r

(3c) + l|AHf [HF] (^)

3(d) AH

r

(3d) + liAH^HF in 118.2 I^O] (A)

3(a) AH,(3e) + liAHf (HFd)]

U(a) AH,(l;a) + AHf [CgF^solid polymer)] - AI^[C0

2

(g)]

U(b) See li(c)

U(c) AH, (lie) + AH

f

[C0

2 (g)] + i|AHf

[HF in 10 1^0] (A)

5(a) See 5 (c

)

5(b) See 5 (c )

5(c) AH, (5c) + AH

f [C0

2 (g)] +l|AHf

[HF 3ji 20 E^O] (X)

6(a) 5s[AI^,(6a) + AH^ [CgF^ (solid polymer)]

6(b) See 6 (c

)

6(c)

7

AH

r

(6c) +AH

f

[C0

2 (g)]

8 l|AHf

[KF(c)] -AH,(8)

9 llAH^CNaFd)] -A^O)

16
Figure 1. Recent information on the heat of formation of aqueous hydrofluoric acid* Upper curve, Cox and Harrop [19] ; Lower curve, Wagman, et al.

[21]; A cycle for BF3-HF set up by Johnson, Feder and Hubbard [15] gives

point (l) when applied to data of Domalski and Armstrong [li-t.], and point

(2) when applied to data of Johnson, Feder, and Hubbard [15] for BFo • The

heat of formation of CFk determined by .Domalski and Armstrong [17] by

combustion of graphite in fluorine is applied to data relating CF^ to HF of

Good, Scott and Waddington [11] to obtain point (3); to the data of Cox,

Sundry, and Head [13] to obtain point (j^); and to the data of Neugebauer

and Margrave [12] to obtain point (5). A study relating NFo to HF reported

by Sinlce [16] is used to obtain point (6)* A study of the H9-F2-H2O reaction

by King and Armstrong [18] gives point (7). The central solid curve shows an

estimate of the probable best values for AHf [HF(aq)] # The dashed curve

differs from the solid central curve by an amount showing the effect of

using the heat of formation of CF]^ determined from the combustion of 11 Teflon”

in fluorine [17 ] on the calculations

.

17
78.0

18

0/HF
Chapter 2

HEAT CAPACITY AND THERM3DYNAMIC PROPERTIES OF

BERYLLIUM NITRIDE, Be^, FROM 20 TO 315 K.

George T. Furukawa and Martin L. Reilly

Abstract

The heat capacity of beryllium nitride, Be 3N2 , was determined

from 20 to 315 K and the thermodynamic properties calculated from

0 to 315 K. The entropy at 298.15 K was found to be 3h»h ±0.3

J deg - -*- mol-

-*- (8.23 ±0.08 cal deg

- -*- mol"-*-).

I. Introduction

The results of heat-capacity measurements on beryllium nitride,

Be^^, presented between 20 and 315 K in this paper have been obtained

in connection with a research program at the National Bureau of

Standards to provide thermodynamic data on light-element compounds.

In connection with this program, the high-temperature enthalpy measurements have previously been reported by Douglas and Payne [1], Earlier,

Satoh [9] reported relative enthalpy measurements at three temperatures

in the range 273 to 773 K on a sample of 98.13 percent purity, the

impurities being O. 78 , O. 87 , and 0.22 percent BeO, Fe20o, and Si02

,

respectively. Recently Justice [2] reported measurements in the range

25 to 310 K on a sample of 96.7 purity.

II. Apparatus and Method

The low-temperature heat-capacity measurements were made from

about 20 to 315 K in an adiabatic calorimeter of a design similar in

principle to that described previously [10]. (The measurements were

made initially from about 80 K, but the measurements above 315 K were

discontinued when small heat effects were observed above 320 K. The

results presented in this paper are based on the data obtained subsequent to heating above 320 K.)

The calorimeter vessel, after filling with the Be^^ sample, was

sealed by means of a specially designed gold -gasket closure [7] and

suspended within the adiabatic shield by means of a Nylon string instead of the filling tube shown in the above reference. The average

temperature of the adiabatic shield was sensed relative to that of the

19
outer surface of the double -walled sample vessel by means of fourjunction constantan-Chromel-P thermocouples and was controlled automatically by means of a combination of electronic and electromechanical

equipment. Heater wires were wound bifilarly in grooves on the

cylindrical! surface and on the conical ends of the adiabatic shield to

achieve good thermal contact. Details of the design of the calorimeter

used, its operation, and the automatic adiabatic control system will

be described in a later publication.

The platinum resistance thermometer (laboratory designation:

10578U9) used in the measurements was calibrated in accordance with

the International Practical Temperature Scale of 19U8 [11]. The

temperatures in degrees Kelvin (K) were obtained by adding 273*15 deg

to the temperatures in degrees Celsius (C). Below 90 K, the thermometer

was calibrated on the NBS-1955 provisional scale which is numerically

0.01 deg lower than the former NBS-1939 provisional scale [8]. The NBS1939 provisional temperature scale is based on a set of platinumresistance thermometers that were compared against a helium gas thermometer. The thermometer resistance measurements were made to the nearest

0.00001 ohm. Initially a manual Mueller bridge was used and later an

automatic Mueller bridge. The resistance -time observations obtained

with the automatic bridge were analyzed by means of a computer to

calculate the heat capacity. The observations with the manually

operated bridge were processed by means of a desk calculator.

The electrical power introduced into the calorimeter heater (100 _n.

)

was measured by means of a Wenner potentiometer in conjunction with a volt box, standard resistor, and saturated standard cells, which were

all calibrated at the National Bureau of Standards. A constant-cur rent

power supply stable to 10 ppm or better was used to facilitate the

power measurements . The duration of each heating interval was measured

by means of a high-precision interval timer operated on the 60-Hz

frequency standard provided at the National Bureau of Standards. The

60-Hz frequency standard is based on a 100-kHz quartz oscillator which

is stable to 0.5 ppm. An electronic counter containing a 1-MHz interval

quartz oscillator was used simultaneously in the measurement of the

heating interval. The estimated uncertainty in the determination of

the heating interval was not greater than ±0.01 sec for any heating

period, none of which was less than 2 min in these experiments.

III. Sample

The Be^N2 sample was specially prepared for the measurements by

the Brush Beryllium Company, Cleveland, Ohio, by reacting pure nitrogen

and beryllium powder at elevated temperatures and crushing the product

to particle sizes between 20 and 50 mesh (0.8 and 0.3 mm sieve openings,

respectively). The material received was thoroughly mixed in a

20
contr oiled-atmosphere box containing dry argon (dew-point: -U0 C)

and samples were apportioned for chemical analysis, for the hightemperature relative enthalpy measurements [1], and for the lowtemperature heat-capacity measurements described in this paper. The

samples for the chemical analysis and the high-temperature enthalpy

measurements were sealed in test tubes under dry argon. The sample

that was poured into the low-temperature calorimeter vessel weighed

97»Ul5g« The calorimeter vessel containing the sample was pumped

at high vacuum and purged with dry helium gas several times and

finally, helium gas at a pressure of 70 torr was sealed in the container with the sample. After completion of the measurements the

calorimeter vessel was opened in the contr oiled-atmosphere box and

the sample was divided and sealed in polyethylene bags for chemical

analysis. The sealed polyethylene bags were placed individually in

screw-cap jars which were in turn placed in desiccators, the whole

operation being done in the controlled-atmosphere box.

The results of spec troc hemic al analysis of the sample are

summarized in Table 1. Only the impurity elements that were detected

are listed. The results of the chemical analyses on the material

before and after the calorimetric measurements are given in Table 2.

For the nitrogen and total beryllium analyses about 0.3 g samples were

first dissolved in dilute hydrochloric acid and the solution diluted

to 250 cc in a volumetric flask. A 10-cc aliquot was analyzed for

nitrogen using the Kjeldahl method, the ammonia being titrated with

0.01 N hydrochloric acid that had been standardized against ammonium

dihydrogen phosphate by means of the Kjeldahl procedure. The total

beryllium was determined by precipitating the beryllium hydroxide in

a 100-cc aliquot with ammonium hydroxide. The beryllium hydroxide was

filtered, ignited, and weighed as BeO. The free beryllium was determined by dissolving 2-g samples in hydrochloric acid. The hydrogen

formed was dried, converted to water, and weighed.

The analysis for water represents all forms of hydrogen present

in the sample. Samples (20 mg) were heated at 10^0 C in a carbonhydrogen-nitrogen analyzer and the amount of water driven off was

determined. The oxygen was determined by a non-destructive lU-Mev

neutron activation technique. Five determinations were Trade using

6-g samples

.

The results of the chemical analysis were found to be inconsistent

and unexpected. The decrease in the free beryllium content in the

samples before and after the measurements can not be attributed to

chemical reactions at temperatures of the measurements. (Small heat

effects were observed above about 320 K. See later parts of this

section for further details.) The difference is probably due to nonhomogeneity in the material, although relatively large samples (2-g)

were used in this determination.

21
The decrease in the total beryllium content because of a chemical

reaction during the heat measurements does not seem possible. If the

observed heat effects resulted from a chemical reaction within the

sample , the expected reaction would be:

3Be(OH)

2 + Be N

2 - 6BeO + 2NH.J . (l)

This should lead to an increase in the apparent beryllium content, since

the ammonia would be lost on opening the sample vessel.

For the material removed from the calorimeter vessel after the heat

measurements, the mass balance for beryllium found is not consistent in

terms of the analyses obtained. The analyses for N, 0, and total Be

sum to 100.01 percent and the addition of H (0.13 percent) found as water

makes the total weight percent 100. 15* This is within the expected

limits of accuracy of the chemical analyses. However, inconsistencies

arise when these analyses are used to obtain mass balance among the

chemical species that are expected to be present (Be^^, BeO, Be(0H)2,

and Be metal). On the basis of the results of the oxygen and water

analyses (2.38 and 1.15 percent, respectively), the percentage of

beryllium as BeO and Be(0H)2 sums to 0.77 percent. When the Be metal

(0.05 percent) and beryllium (57*22 percent) as Be^^, based on the

nitrogen analysis, are added to 0.77 percent, the total beryllium becomes 58.03 percent. This is considerably lower than the total

beryllium (U 8.70 percent) from the chemical analysis. The masses of the

substances present also sum to considerably less than 100 percent

(96.15% - Be 3 N2 * 2.72% - Be (0H)2 , 0.56% - BeO, and 0.05% - Be metal;

9 9 -U7% - total mass). These inconsistencies can be resolved if the

Be metal analysis were higher (about 0.7 percent), but this is not

possible since the estimated error in the chemical analysis for Be

metal is much less than this value.

On the other hand, if the analysis shown in Table 2 for water is

ignored, the remaining analyses would become consistent on the basis

that the substances present are only Be^^, BeO, and Be metal. All

of the oxygen (2.38 percent) would then be taken to be present as BeO,

which corresponds to 3-73 percent BeO or 1.35 percent Be. When the

percentages of Be as Beo^ and as Be metal are added to 1.35 percent,

the total "calculated" Be is 58.61 percent. This is within the limits

of chemical analysis found for total Be (58.70 percent). When the

96.15 percent BeoN2 , based on the nitrogen analysis, is added to the

percentages of BeO and Be metal, the total weight percent is 99*92

percent. The analyses for total beryllium, nitrogen, and oxygen, as mentioned earlier, sum to 100.01 percent. These values are all within

the limits of the chemical analysis.

22
The source of heat effects observed during the measurements

can not be explained in terms of the known possible chemical reaction

within the sample. The possible chemical reaction depicted byequation (l), in which the water from Be( 0 H)2 reacts with Be ^2 to

form BeO and Nth>, is not consistent with the chemical analyses. The

reaction is obviously not possible if the water is securely held at

the temperatures of the heat measurements. Duval and Duval [3]

interpreted their thermal gravimetric analysis work to indicate that

the decomposition of Be (0H)2 starts around 15 0 C and that complete

decomposition of Be(0 H)2 to BeO and H?0 occurs only on heating to

951 C. The observed loss in mass at temperatures below 15 0 C was

attributed to adsorbed water in their sample. If any moisture were

present in the sample that was used in the work reported here, it was

adsorbed between the times the samples was removed from the furnace

and received from the supplier.

After careful consideration of the various possibilities that

could be selected on the basis of the chemical analyses and the estimated uncertainties that would arise from them, the choice was made

to ignore the analysis obtained for water in the reduction of the

heat-capacity measurements. The sample was taken to be 96.23 percent

Be^ll?* 3*73 percent BeO, and O.OI4 percent Be metal and corrections

were applied to the observed values of heat capacity for BeO [5] and

Be metal [6]

.

IV. Re suits

Two series of measurements were made, one on the calorimeter

vessel with sample (gross) and the other on the empty vessel (tare).

The measured energy increments (Q ) and the corresponding thermometer

resistances (R) before and after heating were analyzed on the highspeed digital computer to obtain dQ/dR of the sample as a function of

the thermometer resistance [U ] • The values of heat capacity (dQ/dT)

were then calculated at even temperatures from the dR/dT and the R-T

calibration for the thermometer using the relation:

Briefly, the procedure was to obtain first the best polynomial equation

of the form

to represent the experimental data on the empty calorimeter vessel

(tare) [12]. The polynomial equation was then evaluated at the thermometer resistances observed for the gross measurements in order to obtain

the energy increments for sample only from the observations in the

calorimeter vessel plus sample experiments. The best polynomial

equation giving dQ/dR for the sample only was then obtained.

dQ/dT - (dQ/dR) (dR/dT) . (2)

dQ/dR = E a R

n

n

(3)

23
Figure 1 shows the deviation of the experimental data on the

empty container from corresponding values calculated from the polynomial equation fitted by the method of least squares to the energyresistance observations. The range of the polynomial is from n = -?

to n = +10 (see eq. 3)« Due to increasingly poorer precision at

the lowest experimental temperatures the sample data were fitted

with two overlapping equations . Figure 2 shows the deviation of

the sample data from the polynomial (n ranging from 0 to ii) fitted

to the data over the temperature range 20 to HO K and figure 3

the deviation of the data from the polynomial (n ranging from -2 to

+10) fitted over the temperature range 60 to 31? K. Heat capacity

values calculated from the two equations agreed within 0.02% over

the temperature range 80 to 100 K. The heat capacity values obtained

from the two equations were joined at 90 K. Figures 2 and 3 show the

precision of the measurements and the effect on the final smooth

values of a change of 0.02? percent in the values of the he at -capacity

measurements for the empty and filled sample vessel.

As mentioned earlier heat effects were observed during the

measurements of the heat capacity above about 320 K, and the results

that are presented are based on the data obtained between 20 and

31? K subsequent to heating above 320 K. In figure h are shown

values of heat capacity initially obtained between 80 and 31? K

prior to heating above 320 K. Above 1?0 K, the values of the initial

measurements and those after heating above 320 K are shown to be

essentially the same. Below 1?0 K, the values of the initial measurements are somewhat higher. Since no data were obtained initially

below 80 K, no comparison can be made below 80 K between the values

before and after heating above 320 K. In the range 80 to 31? K, however, the heating above 320 K did not make a large change in the

heat capacity of the sample, at most about 0.? percent at 110 K. The

comparison shows that the heat capacity of the sample was not affected

grossly when heated above 320 K.

The values of heat capacity of Be3N2 , that were generated at

evenly spaced temperatures from dQ/dR in accordance with eq (2) were

corrected for BeO [?] and Be metal [6] and converted to molal basis.

The molecular weight was taken to be ??.0? g. These molal values

were analyzed further for extrapolation to 0 K. The final selected

values below 20 K are based on the extrapolation of the experimental

heat capacity using the Debye heat-capacity function:

C = 19U3.73 (70?/T)3

(?)

(J deg \iol ^)

2 ?
The values of heat capacity from 0 to 315 K were applied in the

usual thermodynamic relations

^

- hok

=

J 3

3 dt ’ (5)

Sm = l" T

(C/T) dT , 1 J o and

G

T

- H

°0K = ‘V1^

- T S

T

’ to obtain the thermodynamic properties. The values

Table 3

Justice [2] recently reported heat-capacity measurements on a-Be^N2 96.7 percent purity. The significant impurities were

BeO - 2.7%, Be metal - 0.2%, C - 0.1$, and Fe - 0.3$. The entropy

at 298.15 K that Justice [2] reported is 8.157 cal deg"-*- mol"-*-, which

is in good agreement with that ( 8.23 ±0.08 cal deg"-*- mol"-*-) found in

this investigation. The values of heat capacity obtained also join

satisfactorily, in both the magnitude of heat capacity and its slope,

with those derived from the high temperature relative enthalpy

measurements reported by Douglas and Payne [1]. A combined table of

thermodynamic properties from 0 to 1200 K will be submitted in the next

report.

V. References

[1] T. B. Douglas and W. H. Payne, "Be 3N2 and Be0 m A^2^ : High-temperature thermodynamic functions based on recent measurements of heat

capacity at the National Bureau of Standards", Preliminary Report

on the Thermodynamic Properties of Selected Light -Element and Some

Related Compounds, NBS Report 7587, 1 July 1962.

[2] Dow Chemical Company, JANAF Thermochemical Tables, Quarterly

Supplement No. 25, March 31, 1967, under USAF Contract

No. F0U611-67-C-0009.

[3] T. Duval and C. Duval, Anal. Chim. Acta, 53 (19U8).

[h] G. T. Furukawa and M. L. Reilly, J. Res. NBS 69A (Phys . and Chem. ) No. 1, 5 (1965).

[5] G. T. Furukawa and M. L. Reilly, unpublished measurements on BeO.

[ 6 ] G. T. Furukawa and M. L. Reilly, unreported results of analysis

of literature heat-capacity data on beryllium.

(6)

(7)

are given in

25
[7] G. T. Furukawa, M. L. Reilly, and J. H. Piccirelli, J. Res.

NBS 68A (Phys. and Chem. ) No. b, 381 (1965).

[8] H. J. Hoge and F. G. Brickwedde, J. Res. NBS 22_, 351 (1939),

RP1188

.

[9] S. Satoh, Sci. Papers Inst. Phys. Chem. Research (Tokyo) 35_,

888 (1938).

[10] R. B. Scott, C. H. ]yjyers, R. D. Rands, Jr., F. G. Brickwedde,

and N. Bekkedahl, J. Res. NBS 35_, 39 (1955), RP1661.

[11] H. F. Stimson, J. Res. NBS 65A (Phys. and Chem.) No. 3, 139 (1961).

[12] P. Walsh, Comm. ACM 5 , 511 (1962).

26
Table 1. Summary of Spectrochemical Analysis of the Sample of

Beryllium Nitride 9 Be^N^ . Impurity Elements that were Detected.

Element Wt. % Element Wt. %

A4 0.001 - 0.01 Mg 0.001 - 0.01

Ca < 0.001 Mn < 0.001

Cr 0.001 - 0.01 Ni 0.001 - 0.01

Cu < 0.001 Si 0.01 - 0.1

Fe 0.01 - 0.1 Ti 0.001 - 0.01

Analysis by: ELizabeth K. Hubbard

Spectrochemical Analysis Section

27
Table 2. Chemical Analysis of the

Sample of Beryllium Nitride, Be^N^

Original Sample

Wt. % Wt. %

Be (total

)

U9.06 N h9.hS

U9.09 U9.52

U9.8U

mean . .

.

U9.08

mean . .

.

U9.60

Be (free

)

0.09 Ci <0.02

0.11

0.09 F <0.01

mean . .

.

0.10

Sample Removed from Calorimeter Vessel

Be (total) 48.72

48 .68

N 48.97

48.89

mean . .

.

48.70 mean . .

.

48.93

Be (free) O

O

•

• O

O

1^0 1.16

1.12

mean . .

.

0.04 mean . .

.

1.14

0 2.38 (average of 5 determinations)

Chemical analysis by: R. A. Paulson

Microchemical Analysis Section

Oxygen analysis by activation method: S. Nargolwalla

Activation Analysis Section

28
TABLE 3 THERMODYNAMIC FUNCTIONS FOR BERYLLIUM NITRIDE (BE^)

SOLID PHASE

GRAM MOLECULAR WT. =55. 0500 GRAMS

T DEG K = 273.15 + T DEG C

CAL=4 • 1840 ABS J

T -( g t"h

o )/t <H G -H G )/T ( S -S G 15 ) t ^o’

(H

t "o’ $ -<G?“*o’

DEG K CAL CAL CAL CAL CAL CAL

DEG MOLE DEG MOLE DEG MOLE MOLE DEG MOLE MOLE

.00 .000 .000 .000 .000 .000 .000

5.00 .000 .000 .000 .000 .000 .000

10.00 .000 .000 .000 .003 .001 .001

15.00 .000 .001 .001 .017 .004 .006

20.00 .009 .003 .003 .053 .011 .013

25.00 .002 .005 .007 .129 .021 .043

30.00 .003 .009 .012 .267 .035 .089

35.00 .005 .014 .019 .490 .055 . 165

40.00 .007 .021 .028 .828 .081 .280

45.00 .010 .029 .039 1.314 .115 . 446

50.00 .014 . 040 .053 1.991 .158 .676

55.00 .018 .053 .071 2.910 .212 .985

60.00 .023 .069 .092 4.133 .280 1.390

65.00 .029 .088 .118 5.736 .364 1.913

70.00 .037 .111 .148 7.800 . 464 2.575

75.00 .045 .139 . 184 10.411 .584 3.404

80.00 .055 .171 .226 13.671 .724 4.427

35.00 .067 .208 .275 17.685 .886 5.677

90.0 0 .080 .251 .331 22.557 1.066 7.186

95.0 0 .095 .299 .393 28.379 1.266 8.994

100.00 .111 .352 • 464 35.248 1.485 11.134

105.00 .130 .412 .542 43.265 1.725 13.645

110.00 .151 .478 .628 52.531 1.984 16.568

1 1 5 . 0 C .173 .5 49 . 722 63.138 2.261 19.941

120.00 . 198 .626 .825 75.172 2.555 23.805

125.00 .226 .710 .935 88.715 2.865 28.202

130.00 .255 .799 1 .054 103.94 3.188 33.172

135.00 .237 .893 1.181 120.52 3.525 38.755

140.00 .321 .994 1.315 139.12 3.874 44.991

145.00 .358 1.099 1.457 159.38 4.234 51.919

150.00 .397 1.210 1.607 181.47 4.602 59.576

155.00 .439 1.325 1.764 205.42 4.978 68.000

160.00 .483 1.445 1.928 231.26 5.362 77.228

165.00 .529 1.570 2.099 259.04 5.750 87.292

170.00 .578 1.699 2.276 288

7 7 6.143 98.228

175.00 .629 1.831 2 .460 320.47 6.538 110.07

1 8 0 . 0 0 .632 1.968 2.650 354.15 6.935 122.84

185*00 .738 2.107 2.845 389.83 7.334 136.58

190.00 .796 2,250 3.G46 427.49 7.732 151.30

195.00 .357 2.396 3.252 467.14 8.129 167.05

200.00 .919 2.544 3.463 508.78 8.525 183.83

205.00 .984 2.695 3.678 552.39 8.919 201.69

210.00 1.051 2.847 3.898 597.96 9.310 220.63

215*0;, 1.119 3.002 4.122 645 .48 9.698 240.67

220.00 1 . 190 3.159 4.349 694.93 10.083 261.85

225.00 1.263 3.317 4.580 746.31 10.465 284. 17 230.00 1.333 3.476 4.814 799.58 10.843 307.65

235.00 1.414 3.637 5.051 854.73 11.216 332.31

240.00 1.4Q2 3 .7Q9 5.291 911.73 11.585 358.17

245. OC 1.572 3.962 5.534 970.57 11.950 385.23

250. OC 1.654 4.125 5.779 1031.2 12.309 413.51

255.00 1.737 4.239 6.026 1093.7 12.664 44 3.02

2 60.0 1.822 *•.453 6.275 1157.3 13.012 473.78

265.00 1.909 4.618 6.527 1223.8 13.355 505.78

270.00 1.906 4.783 6.779 1291.4 13.693 539.05

273.15 2.053 4.887 6.939 1334.9 13.902 560.65

275. OC 2.086 4.948 7.034 1360.7 14.024 573.58

2 8 0 . 0 C 2 . 176 5.113 7.289 1431.6 14.350 609.39

285.00 2.268 5.278 7.546 1504.2 14.670 646.47

290.00 2.362 5.442 7.804 1578.3 14.985 684.85

295.00 2.456 5.607 8.063 1654.0 15.294 724.52

298.15 2.516 5.710 8.226 1702.5 15.486 750.17

300.00 2.552 5.771 8.322 1731.3 15.598 765.48

305.00 2.648 5.934 8.583 1810.0 15.897 807.74

310. OC 2.746 6.097 8.844 1890.2 16.187 851.31

315.00 2.845 6.250 9.105 1971 .

3

16.468 896.18

H *0 AND s

o APPLY TO THE REFERENCE STSTE OF THE SOLID AT ZERO DEK K •

29
4) M

3

4-> «

M

0)&4> H

(•o*[»3- *sqo) uo*pa»TA9a 0§*^uao^9^

30

Fig.

1.

Percentage

Deviation

of

the

Empty

Sample

Vessel

Heat

Capacities.
Percentage

Deviation

(Obs.-Calc.)

o

Temperature, °K

Fig. 2. Percentage Deviation of the Beryllium Nitride Sample Heat Capacities.

31
.025$

OF

GROSS

OBSERVATIONS

Z *0+ T’Of 0 x*0- 3*0-

(•OT»0-*sqo) uo^l*TA®a

32

Fig*

3.

Percentage

Deviation

of

the

Beryllium

Nitride

Sample

Heat

Capacities
33

Percentage

Deviation

of

Initial

Measurements

from

the

Beryllium

Nitride

Sample

Heat

Capacities
Chapter 3

AUTOMATIC DATA REDUCTION APPLIED TO BOMB CALORIMETRY

OF ORGANIC FLUORINE COMPOUNDS*

George T. Armstrong

Thermochemistry Section

Abstract

• \ Subroutine FARMST, to calculate the combustion energy of

organic fluorine compounds from oxygen -bomb calorimetric data, has

been prepared following the computational procedure of Good and

Scott. The subroutine is written in FORTRAN IV and conforms to the

more general program of Shomate for C-H-O-N-S compounds. The

Shomate program has been modified to allow introduction of subroutine

FARMST, and to change the calculations in several procedural ways

including presentation of the result in joules.

This work was supported, in part, by funds from the Department

of the Navy.

3k
1. Introduction

Shomate [l] prepared a general program for reduction of the

data from bomb combustion of organic compounds containing the elements

C-II-O-N-S, following the computational procedure of Hubbard, Scott,

and Waddington [ 2 ]. He recently [la] modified his program to

FORTRAN IV, and' segmented it into subroutines. We have made

additional modifications in order to improve the versatility of the

program, to render the results in joules, and to introduce the new

subroutine FARMST.

We have written subroutine FARMST to allow the reduction of

data involving fluorine as well as C-H-0-No For this reduction a procedure for hand computation was previously reported by Good

and Scott [j] 0 This procedure is followed in FARMST. The procedure

does not make provision for handling compounds containing both S and F

together.

35
2. New variables in the program

In order to make the general modifications outlined above new

variables were defined in the program0 Many of these took the form

of additions to the array W. It is useful to place variables here

because W has the property that it can be modified by the input data

cards, and the values in it are available for a memory print -out

associated with any experiment. Array W has 999 terms, of which some

673 are used. A complete listing of the variables in this array is

given in Table 18 Of these W(l) to W(22), W(l09), W(206 ), W(226),

W(246), W(266 ), w(286), and W(59l) to W(673) have not previously

been defined. In addition the definitions of W(572) and W(573) were

changed. Tables of data needed in subroutine FARMST were introduced

into DATA as block data. These are W5IAF, a table of solubilities of

CO2 in aqueous HF solutions, obtained from Cox and Head [4]; W87AF,

a table of energies of solution of CO2 in aqueous HF solutions, also

obtained from Cox and Head [4]; W71AF, a table of dilution energies

for aqueous HF, taken from Wagman, et al. [ 5 ]; W72A, W73A, W7^A,

and W75A, tables of properties of aqueous HF solutions taken from

Good and Scott [3 ].. Unfortunately the latter tables are given only

at 25°C, so that the computation is limited in .the adequacy with

which it can be applied to other temperatures.

Values for the solubility of CO2 are given by Cox and Head [^]

for concentrations of HF from 0 to Values at 6$ were estimated

by extrapolation and inserted in the array of data in order to allow

use of the quadratic interpolation formulas given in the program for

interpolation in the region from 4 to 5 percent. The data for the

energy of solution of CO2 was similarly extrapolated.

Data from Wagman, et al. [ 5 ] were smoothed. The point at HF-IOH^O

appears to be somewhat irregular and a fictitious value must be used

at 0$ HF, in order to allow reasonable interpolation from 1 to 2$.

36
Values at 1 percent intervals were taken from the smooth curve

to form the data array to be used in the computations. In all the

above cases quadratic interpolation is used. Where temperature is

known as a variable, a two-fold quadratic interpolation is used.

Table W71AF is not suitable for interpolation in the region 0 to 1

<jo HF.

37
Table 1.

TABLE OF TUERMOC1IEMICAL VARIABLES

EXPANDED FOR FARMST SUBROUTINE

Term of the Value or meaning, and units

W array

1'2

3

4

5

6

78

9

10

11

12

13

14

15

16

17

18

19

20

1 . 273.15

298.15

101325

22413.6

4.184

The constant unity

The ice point temperature, °K

The standard reference temperature, 25 °C.

The standard atmosphere, NirT^

3 The standard molar volume of a gas, cm

The thermochemical calorie, J

The gas constant, R = 8.314325 J mol"^, defined

by R = 0.000001 * W(4)/W(2).

The gas constant, R = 1.9871715 cal mol""-*-, defined

by R = W(8)/W(6)

The gas constant, R = 0.0820560 cm^ atm, defined

by R = W(5)/W(2) * 0.001

Molecular weight of water, defined by

W(ll) = 2. * W(559) + W (560)

Molecular weight of carbon dioxide, defined by

W (12) = W(558) + 2. * W(560)

Molecular weight of nitrous acid, defined by

W(13) = W(559) + W(561) + 2. * W(560)

Molecular weight of nitric acid, defined by

W(14) = W(559) + W(561) + 3. * W(560)

Molecular weight of sulfuric acid, defined by

W(15) = 2. * W(559) + W(562) + 4. * W(560)

Molecular weight of RF, defined by

W(16) = W(559) + W (563)

38
21

O O 23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

Table 1. (continued).

Th - 25. , defined by W(21) a W(148) - 25.

Th + 273JL5, defined by W(22) « W(148) + W(2)

Mass of substance

Mass of substance

Moles of substance

Vi [bomb] } dm3

Vi[H20 (total) ] } dm3

Pflgas] f atm

Mj. [Il20 (total) ] g

N-jJb^CKtotal) ] y mol

Vitgas] , dm3

N-j_[ H20(vapor) ] , mol

Nf[ H20 (liquid) ] } mol

Nf[gas] mol

Nf[ (O2 + N2 ) (dissolved)] f mol

Nj[[02 + N2 ) (total)] ; mol

Nf [ HNO3 ] , mol

Nf [KN02 ] , mol

Nf[H2 S04 ] , mol

Nf [H2 O (liquid) ] , mol

Mf [Solution)

]

(Weight per cent) £ [H2 SO4 ] (Weight per cent) f [HNO3

4- HNO2 ] (Density) f [Solution] , g dm" 3

Vf [Solution]

(Normality) £ [H2 SO4.] mol dm" 3

(Normality) f [HNO3 + HN02 ] , mol dm

" 3

Nf [H2 0 (liquid) ]/Nf [H2 S04 ] Vf [Gas] dm^

Nf [COfj (total)] } mol

Kf [C02 ] Df [C02 ] K* ICO,]

N£ [CO2 (dissolved)] , mol

Nf [CO2 (gas) ] y mol

39
56

57

5S

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

Table 1. (continued),

Nf [ (Oo + N2

) (total) ] j mol

Kf [02 ] Df [ 02 ]

[ 02 ] Nf [ (02 + N2

) (dissolved)] f mol

Nf [ (0

2 + N2

) (gas)] f mol

Nf [gas] } mol

Xf [C0

2

] } (mole fraction)

U

f [gas]

P

f [gas] , atm

G

Nf [H2 0 (vapor)] , mol

[ (dE/dp).j,] f [solution] J mol" 1 deg

AE (dilution) [HNO

3 + KN02 ] , J mol" 1 AE (dilution) [^SC^] J mol

" 1

E [calorimeter] , J deg

" 1 _ ]_ Ef [contents] , J deg

Ef [contents] ? J deg" 1 AE (ignition) J

Ti , deg G

Tf , deg G

AT (correction) deg

[AE (vaporization)

] f [H

2

0] , J

AEf [

H

2 0] from 1 to Pf , J

AEf [substence] from 1 to Pf } J

[AE (solution)] [ 0

2

-f- N2 ] } J

AEf (gas) from O to Pf , J

AE (isothermal bomb process) } J

[AE (solution)]

f

[C0

2

] J

[AE (solution)] f

[ 0

2 + N

2

] } J

AE

£ [solution] from 1 to Pf , J

[AE (dilution)]

f

[KNO3 + HN0

2

] , J

[AE (dilution)] f [H2 S04 ] , J

ho
92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

Table 1. (continued)

[AE (decomposition)] £ [HNO34* HNO2 ] , J

AE £ [gas] from p£ to 0 , J

[AE (vaporization)] £ [l^O] , J

Sum of W (81) to W (94) inclusive, J

Combustion energy from auxiliary material , J

Combustion energy from fuse , J

Combustion energy from compound , J

AEc/M [compound] at , J

AEc [compound] at , J

AHc [compound] at , J

AHc [compound] at 25 deg C , J

AHf [compound] at 25 deg C , J

A subscript (cA) in empirical formula of bomb contents

B

" " (%) it it 1 t 1 1 11 11

C

' 1 (°c)

11 it 1 1 1 1 11 it

r»

1

1

( ND>

ti 11 1 1 1 t 11 ti

E

' ' (SE

) ti 11 1 1 1 1 11 11

F

' ' ( ff^

11 11 1 1 i 1 11 ti

( ) " (

)

11 11 1 1 1 1 11 t 1

( ) ” (

)

11 11 1 1 1 t it ti

( ) " (

)

11 it t 1 1 1 11 11 N£ [N*] j extra nitrogen , mol

Weight of platinum in air , g

Weight of glass in air , g

Weight of other materials in air , g

Mass of platinum (weight in vacuum) , g

Mass of glass (weight in vacuum) , g

Mass of other materials (weight in vacuum) , g

3 Volume of platinum , dm

3 Volume of glass , dm

Volume of other materials , dm^

3 Free space in rigid glass bulb , dm

Nitrogen in free space , mol

Initial period rate , deg min”^

Final period rate , deg min“^

hi
127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

Table 1. (continued)

X [O2 + N2 ] , mole fraction

X [N* ] , mole fraction

Mu [

O

2 ] , see item W(64)

A (C of solution) , see item W(76) , cal dcg"^

E [calorimeter] * (T^ - T^ - AT (correction)) , J

E^ [contents] * (Tj[ - T^) , J

E^ [contents] * (T^ - T^ + AT (correction)) , J

AH (vaporization) [l^O] } for W(81) and W(94) , Cooling constant , min"^

Area under Temperature vs. Time curve , deg min

Time (start of main period) , min

Time (end of main period) , min

Temperature (start of main period) , deg

Temperature (start of main period) , deg

Mid-time (time after start of main period) , min

Rotation time , min

Heat of bomb rotation , deg min*”^

Sum of terms W(81) , W(82) , W(84) , W(85) , W(88 ) , W(89),

W(93) , W(94) , W (83) , J

Corrected temperature rise , deg

Pressure to which the bomb was filled , atm

Temperature at which the bomb was filled y deg C

T-n , the selected temperature y deg C

T^ , predetermined value of T^ y deg C

Pressure of N£ in glass bulb y atm

/

; Coefficients used to calculate values of items at

} temperature T^ from values at 20, 25, and 30 deg C.

i Selected ratio Nf [l^O]/^ [^SO^]

Actual ratio Me [^Oj/Nf [H2 SO4 ] AHj- [E^SO^] at selected ratio , cal mol"^

AKf [l^SO^] at actual ratio , cal mol”^

Combustion energy from 1st impurity , J

Combustion energy from 2nd impurity , J

Density of air (if zero , item 567 is used) , g cm

k2
161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

17S

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

Table 1 . (continued).

C of H2SO4 solution (selected concentration) , cal g"^- deg“^-

ACp/AT of H2SO4 solution (selected concentration) } cal g“^

deg-2

Density of 1^0 f g dm“^

Reference ratio Nf [l^O]/ N£ [ HF

]

b3
195

196

197

19S

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

Table 1. (continued)

Number of C atoms in compound

it f 1 A

11 11 1 I

IT I I ©I 1 If IT

ii * ? N11 11 * I

IT I I 3

It I I t I

ii 1

T

F

i • i i ii

It II

^ ^ II II II

IT II

^ ^ II II II

II II

^ ^ II II II Hass of compound (weight in vacuum) } g

Molecular weight of compound

Moles of compound

- 3 Density of compound } g cm

Volume of compound dm

Weight of compound (in air) } g

Cp of compound ; cal g”l deg’^

(AV/AT)p of compound , dm^ deg

-

"^ g“^

(AE/AP)rp of compound J atm“^ g

^

AE

C [compound] J g’^

AEC [compound] J mol”^

Number of C atoms in auxiliary material

ii i i hi i i i ii ii

ii I? o

ii ii ii it

ii T 1 M

ti ii ii ii

ii i i gii ii ii ii

ti i

i p

ii ii ti ti

ii ii

^ ^ ii ii ii ii

ii ii

^ ^ ii ii it ii

ii i

i ^ ^

i i ii ii ii

kb
230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

Table 1. (continued).

Mass of auxiliary material (weight in vacuum) , g

Molecular weight of auxiliary material

Moles of auxiliary material

_ O Density of auxiliary material ; g cm J

Volume of auxiliary material , cm

Weight of auxiliary material (in air) , g

Gp of auxiliary material, cal g" 1 deg" 1 (AV/4T)p of auxiliary material , dnP deg" 1 g" 1 (AE/AP)^ of auxiliary material , J atm" ^ g" 1 AEQ [auxiliary material] , AE C [auxiliary material] , Number of G atoms in fuse

J s

" 1 J mol”^

I I " H >' It II

i r i i 0

11 II it

i i '

' N

ii 11 II

i i ' f S' ' II II

i i • ip ii II II

i i ,,

( } ,,

II II

i i ii

( > i, II II

i i II / \ II If 11 Mass of fuse (weight in vacuum) , g

Molecular weight of fuse

Moles of fuse

Density of fuse , g cm Volume of fuse , dm ° Weight of fuse (in air) , g

Cp of fuse , cal g”l deg** 1 (AV/4T)p of fuse, dm^ deg“ ^ g

1 (AE/AP)^ of fuse, dm^ atm**^- g

1 AEC [fuse] , J g' 1 AEC [fuse] , J mol" 1 Number of C atoms in first impurity

i r 1 ' H1 ' 1 ' 1 r 11

ii t i o

11 11 * t ii

it ii it it it i i

U5

N
265

266

267

26S

269

270

271

272

27 3

274

275

276

277

278

279

280

281-

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

Table 1. (continued).

Number of S atoms in first impurity

ri ’

* F

11 1 ’ i r r i

ir i i ^ ^

i r i r it r i

r i t i ^ ^i i it ii r i

ii ii

^ ^

ii ii it ii Hass of first impurity (weight in vacuum) , g

Molecular weight of first impurity

Moles of first impurity

Density of first impurity , g cm"3

Volume of first impurity } dm^

Weight of first impurity (in air) , g

Cp of first impurity , cal g"-*- deg"^

(AV/AT)p of first impurity ; dm ^ deg"^ g~^

(AE/AP)^ of first impurity } J atm”^ g”^

AEC [first impurity] J g”^

AEC [first impurity] ; J mol“l

Number of C atoms in second impurity

1 1 ,

. H

> • i t i t i i

1 I i i 0 " i t i i i i

1 1 » i N

t i i i i i

1 1 i i s " t i i t i t

1 1 | i f

11 t i i i i i

1 1 i,

( ) ,, t i i i t t

I 1 ,,

( ) ii t i i t i t

1 I ii / \ ii i i i i i i Mass of second impurity (weight in vacuum) g

Molecular weight of second impurity

Moles of second impurity

_3 Density of second impurity , g cm

Volume of second impurity , dm

Weight of second impurity (in air) } g

C of second impurity , cal g"-*- deg”^

(AV/AT)p of second impurity , dmJ deg”^ g

(Z^E/AP)^ of second impurity , J atm”^ g

^

4EC [second impurity] , J g'^

U6
Table 1* (continued)

300 4EC [second impurity] , J mol"^

301 - 400 Recorded times at which corresponding temperature

readings in locations 401-500 vere taken, minutes

401-500 Recorded temperatures of the initial, main, and final

periods, introduced in ohms and converted by the

program to degrees C.

501-550 Bridge dial corrections , ohms

551 Ten- ohm dial setting, nominal value, ohms

552 Ten-ohm dial setting correction , ohms

553 Average correction to convert N-only or R-only readings

to (N + R) /2.

554 Bridge-zero correction

555

556

557

558 Atomic weight of C (12.01115)

559 Atomic weight of H (1.00797)

560 Atomic weight of 0 (15.9994)

561 Atomic weight of N (14.0067)

562 Atomic weight of S (32.064)

563 Atomic weight of F (18.9984)

564 Atomic weight of

565 Atomic weight of

566 Atomic weight of

567 Density of Air , 0.0012 g cm” 3

568 Density of weights , 8.4 g cm~3

569 Density of platinum ,2145 g cuf

570 Density of glass , 2,24 g cm*" 3

571

m O Density of other material , 1.0 g cm

572 Density of water g/1000 cm3

573

574 0.0

575

•j AEC /M for benzpic acid calculated by program , J g” x 576 AE

C /M for benzoic acid, certified value = 26.434 kJ g

577 Cp of platinum = 0.0325 cal g“^

578 Cp of glass = 0.17 cal g“^

b7
579

5S0

581

582

583

584

585

586

587

588

589

590

591

592

593

594

595

596

597

598

599

600

601

602

603

604

605

606

607

608

609

610

611

612

613

Table 1. (continued).

Cp of other material , = 0.0 cal g

” 1

C

p

of C02 , gas, at 25°C , 0.20163 cal g

" 1 deg-1

AC

p

/AT of CO2 = 0.0 cal g

" 1 deg” 2

C of O

2 , gas, at 25°C , 0.219375 cal g

" 1 deg”-*- AC

p

/AT of O

2

=0.0 cal g

” 1 deg

" 2

C

p

of N2 , gas, at 25°C, 0.248465 cal g

" 1 deg" 1 ACp/AT of N2 = 0.0 cal g~^ deg”2

C

p

of H

2 0, liquid, at 25°C , 0.99895 cal g

" 1 deg

” 1 ACp/AT of H2 0 = 0.0 cal g

” 1 deg

” 2 ACp/AT of smaple =0.0 cal g

1 deg

” 2

AHf[C02 (gas)] = -2137.0552 cal g

" 1 AHf [H

2 0 (1)] = -3 792.04 cal g

" 1 AH vap [1I2

0] = 10 177 cal mol-l

AE decomp [HNCh ] = 14 074 cal mol”l

AS decomp [EN02

] = '**6 600 cal mol ^ AE vap [EF from HF (a q). ] = 11 000 cal mol

" 1 AEf [EF in lOI^O] = -76 235 cal mol" 1 AH or AE hydrolysis [CF4 ] = *41 500 cal mOl

” 1 Cp [CF^] = 14.7 cal mol” 1 deg

” 1 AC

p

/AT [CF4

] = 0

C

i

[HF (vap)]

(Normality) ^ [HNO3 ] , m mol cm

” 2

K. [02

] [HF (vap)] , mol

Hi [02] Nf [HF (total)] , mol

% [CF4

(total)] , mol

N* [HF (total)] , mol

Njr [H2 O (total)] , mol

(Weight per cent)^ [HNO3 ] (Weight per cent)^ [HF]

Nf [HF (ag)] , mol

Err [H

2

0] /N^[HF] , actual ratio

U8
614

6 15

olo

617

6 18

619

620

621

622

623

624

625

626

627

628

629

630

631

632

633

634

635

636

637

638

639

640

641

642

643

644

645

646

647

Table 1. (continued).

[IIqO] / £ [HF] , selected ratio

Cf [UF (vap)]

(dE/dp)„. [solution] } cal atm"”'*" (dE /dp) £ [solution] } cal atnf^-

[solution]

Ajj [solution]

[11F (gas)] , mol

(Norma lity)£ [11F] , mmol cm"^

AEf [C02

] /Nf [C0

2

] cal

Mole fraction (X) [CF^]

AE dilution [HF (final) ] _,cal

Nf [H2 0] /N£ [HF] } selected ratio

Weight per cent IiF at selected ratio

Weight per cent KF at N£ [H^O] /N^ [HF] = 10

All£ [HF (aq ; selected ratio] , cal mol**-*- [H

2 0] , mol

AH

f [KF (aq, selected ratio)] - AH£ [HF (aq, 10H2 0) ] } cal

mol“ 1 AHf [HF (aq, 10H

2 0)] - AH£ [HF (aq ; actual ratio)] , cal mol" 1 M^ [solution] , g

(AE vap)^ [KF] } cal mol

- ^

(AE vap)- [HF] y cal mol”^

r -i

AE dilution [KF (total)] } cal mol

^ [KF] , g

Molar coefficient of CF

4 in equation

Correction for CF^ hydrolysis , cal

Cp [HF (aq, selected ratio)] , cal g” 1 Molar coefficient of 02 in equation

Molar coefficient of II2 O adjusted for hydrolysis of CF^.

Molar coefficient of C0

2 adjusted for hydrolysis of CF^

Molar coefficient of N- in equation

Molar coefficient of HF adjusted for hydrolysis of CF^

h9
64S

649

650

651

652

653

654

655

656

657

658

659

660

661

662

663

664

665

666

667

668

669

670

671

672

673

Table 1. (continued)

AN [gas ] , mol

AJijc [CO

2 (g) ] } cal mol”^

Allf [H2 O (l)] y cal mol ^ Moles idealized actual HF (aq, selected ratio)

Moles idealized actual II2 0

Moles idealized actual CO2 Moles 1^0 reacted (excludes "water in HF (aq, selected ratio^)

M. [HNO3 ] , g

(Weight per cent)^ [HF]

(Weight per cent)-^ [HNO^]

[solution] , g cm"^

[solution] , 1000 cm^

^i

ATI at 25° C [adjusted reaction] , J mol”^

AE at 25° G [adjusted reaction] } J mol ^ AE at 25° G [unadjusted reaction] , J mol"'''

AHf [compound] at 25° C, J mol”^

AEf [compound] at 25° C, J mol”^

AH^ [

H

2

S 0^ (aq, selected ratio)] , J mol"^- , = W(156) * W( 6 ) AKf [^SO^ (aq, actual ratio)] J mol’^ , = W(157) * W( 6 ) AE [Reaction] at 25° C } adjusted for hydrolysis of CF^,

, ,-l cal moi

AE [Reaction] at 25° C ,

' ' " ' 1 " "

i t " 1 cal mol

AE [Reaction] at 25° C } unadjusted } cal mol”"^

AEjc [Compound] at 25° C , cal mol”-*-

AEf [Compound] at 25° C } cal mol”!

AH [Reaction] at 25° C, unadjusted , cal mol ^

50
3* Subroutine FARMST

The practice initiated by Shomate, of numbering variables in

the W array, so far as possible, to conform to the number of the

calculational step given by Hubbard, et al, [ 2 ] is continued here

by numbering them to conform to the computational steps given by

Good and Scott [ 3 ]* These authors have made their work mutually

consistent to a large degree. It is. not possible to follow this

practice throughout, however, because in order to retain mutual

consistency with Hubbard, et al G , Scott and Good introduced multiple

variables of the same step number. We have assigned some of these

variables higher numbers (above W( 590 )) more or less as they are

encountered in the calculation. The subroutine begins with the

calculation of W(29 )> as all prior steps are identical in the two

programs. The subroutine then bypasses the major part of the program

called HOWARD, following a parallel but different set of calculations

to arrive at final energy values. Where an identity could be

established between a variable of FARMST and a variable of HOWARD,

i.e, as to meaning, the same variable designation was used in

FARMST.

In calculating the composition of the initial bomb contents

and the final bomb contents, the program assigns temporary values

to the amounts of water and HF present in the liquid phase, and of

C02 (g), [n2 + 02 ](g), H20(g), and total gas, present in the gas

phase. These are then adjusted after one pass through the calculation,

and the calculation of the quantities is repeated.

In mathematical expressions used at various stages of the

computations. Good and Scott [ 3 ] used expressions valid at 2p°C, whereas

in similar instances Hubbard, et al. [ 2 ] used expressions containing

terms with temperature as a parameter. Where the correspondence between

equations used showed that the equation used by Hubbard, et al. reduced

at 25°C to that used by Good and Scott, we used the more general

expression of Hubbard, et al. , as did Shomate [l, la].

51
1+. Modifications to the main program and subroutines

The modifications made in the main program HOWARD and subroutines

INPUT, CONVRT, MIDTIM, OUTPUT, and DATA, may be classified as (1)

those necessary to introduce an additional subroutine, which do not

modify the mode of calculation, and (2) those which are matters of

convenience or preference in causing the calculations to have certain

desirable features,,

In classification (l) we refer to changes such as program statements

necessary to allow the program to recognize the new variables

introduced in the subroutine,. These are matters of programming technique

and include definitions of certain variables at suitable times, in

the program or in block DATA subroutine, transfer statements dependent

on the presence of F in the compound, and suitable output statements

to give the appropriate point out.

In classification (2) changes were introduced in order to change

the details of the calculation in certain ways.

Calculations were put in terms of joules wherever practicable.

Where input data, such as tables, were in calories in the original sources,

these were converted to joules before finally being added as energy

terms. The program was restated so that the energy equivalent of the

calorimeter would be in joules per degree, the energies of combustion

of fuse, auxiliary materials, and impurities were in joules per gram,

the ignition energy was in joules, and so on. Output statements were

modified to indicate the new units, A certain number of output variables

were expressed in both joules and calories, and so new variables were

introduced to allow this.

Universal constants and defined constants were introduced in the

block data program where possible, rather than as terms in the numerical

coefficients of equations throughout the program and subroutines. The

algebraic variables were then used in the equations. The reason for

this is to permit ready change of a constant throughout the program,

if it should ever be desirable. Thus the value of the standard molar

volume of a gas, 22^13,6 cm

3 mol~^, is given the name W(5), and the

52
variable W(^) is used wherever the standard molar volume occurs in an

equation. A change in the selected value of W(5) is thus readily

accomplished. Other universal constants introduced in this way include the

ice point, 273 » 15°K, the standard reference temperature, 298. 15°K, the

-2

standard atmosphere, 101^25 Nm , the ratio of the calorie to the joule,

4. 18^ J cal \ and the atomic weights of the elements. Derived

quantities such as the gas constant, R, and the molecular weights of

compounds involved in the calculations are calculated at an early stage

of the program HOWARD.

The molar coefficients of the reactions involved and the change

in moles of gas present were calculated early in the main program.

In INPUT subroutine a statement is introduced causing the

machine to test whether Ti, Tf and AT (corr) have been specified.

If all three are specified, as by means of a

,f 9M card the program

omits their calculation, thus bypassing subroutines CONVRT and MIDTIM.

53
5* Debugging

Subroutine FARMST and the whole program were "debugged” by

running the sample calculation given by Good and Scott [3]. In order

to do this, the data used by Good and Scott were carefully examined for

conformity to the program requirements,, Several adjustments in the

program were made temporarily to assure that the program would

duplicate the results obtained by Good and Scott. These included

setting the density of air equal to zero for the buoyancy correction

so that masses instead of weights in air could be used for the amounts

of substances introduced. A small discrepancy in the bomb volume

(apparently due to neglecting the platinum volume) was discovered.

An adjusted bomb volume was then selected. Values of the CO2 solubility

and heat of solution were dubbed in to allow the calculation to

simulate Good and Scott's.
6. Input Data Cards

Table 2 gives a printout of the input data cards for a run on per f luoropiperidine. Each card is coded in column 1 with a digit

from 1 to 9 which defines the class of information found in it,

following Shomate’s practice. The "l" card contains data concerning

the fuse and auxiliary material. The only deviation from Shomate's

practice in the "1 " card is the use of energies of combustion of

these two substances in joules per gram instead of calories per gram.

These values are found in columns 30“35 and 66-72 respectively. The

,,2" card contains the name of the compound, the numbers of C, H, 0, N

and S atoms in it, and some bomb conditions. The number of F atoms

is introduced later in a

r, 9M card. (Table 2 approximates the card format).

The "3 " card contains data on the amounts of substances present.

The format of this card has been slightly modified to permit weights

to be expressed to micrograms. The revised format is as follows:

Column Format Quantity

1 3

2-3 A2 Run Number

4-11 F8.0 Weight of compound (in air), g

12-18 F7.0 Weight of fuse (in air), g

19-25 F7.0 Weight of auxiliary material

(in air), g

26-32 F7.0 Weight of platinum (in air), g

55-39 F7.0 Weight of glass (in air), g

•

40-43 3PF4.0 Volume of water placed in

bomb, cm

3

44-48 0PF5.

0

Ignition energy, J

49-53 6PF7.

o

Moles of HNO3 formed (X 10 6

) 54 FloO Moles of HNO2 formed (X 10 s

) 55-59 10PF5.0 Pressure to which bomb is filled.

atm

55
OJo OJ CO

OJ

CVJ

OJ

Q) rO

oj H 1—1 Oo H 0 a A A CVJ H o A o o 0 A •

CVJ o A

-d

A ov

CO a -d A -d H a rH rH

rH

AOJa o CVJ A A [

0 a A

-d rH CO

rH

A0 A

00 Oo o O

rHo A

-dA

VO

rH

lf\ rH

t"- CO

CO

0| -dC

c AMQM

cd(8M

PHSsaDu

DM

CVJ

CVI CVAo aH

-d

VO

CO3

-d

rH

rHO O

cvj CO

-dA

CO

CVJ A HM

CdPM

DuO QOOoa§

DuH

<3QO

is

t—i

C/3 DoMa 1oA

£3oQa

sJ

PMP3

C/3 ooHQ

DuH OO o

ovo

LA

COAo vo

-d

r—

vo

rH

-dC

O

rAOaoO

COa&

COo

CVJ at

o AAO arHA

CO

VOt OA

VO

A • o

-d o O o o A 0 rH o

vo

A VO o vo CO vo A cvj

COO

-=? rH o

rH vo

vo vo A CVJ Oo9 VO • rH o O vo VO -d A CVJ

COOO

ONA

VO

CVJ

CVJ o Pd CO 0 Ol Dd fa H H

js CO < -d O

Js S A CO

CO 2 O rH -d O A 0 Pd CO A O rH o rH <3 Du CO A CO rH O A o A 0 • t

CO Du Du

A CVJ O 0 CVJ rH

A

w O O A

A 0 CVJ u- o H rH o co A r A rH A _d CO H H vo vo 1 A M CO CO rH rH VO c0 A -d CO vo

00 pd Pd Dd O o CVJ t

-d rHA o

rH CVI H H H • O o o o VO VOA cvj rH

A -d

A C"A CO CO

A

A

A

A

A

A

56
60 -6k F5.0 Temperature at which bomb is

filled, °C

65-71 F7.0 Density of air, for reducing

weights to vacuum, g cm “3

72 FI. 0 Free space, if any, in rigid

glass sample bulb, cm

3

The moles of HNO2 formed and the volume of free space in the bulb are

usually zero, so those have been reduced to a single column each0 Card "1" contains temperature -time data points. The illustration

shows a possible format if Ti, Tf and AT fcorr) are given0 A single

temperature and time are given in the initial field (terminated by

1 in column 16) and in the final field (initiated by 3 in column 30 ). These may not be necessary. The actual values of Ti, Tf and AT (corr)

are introduced later in a

" 9

" card.

Cards "5

" end ”6" are not used in this program. Card UrJ" gives

commentary which appears in the printout (see Table 3 )°

Cards "8" and M8l n call for memory printout of the W array, as fixed point and floating point format, respectively. In the example,

the W array from W(001) to W(673) inclusive is called for.

Cards " 9

" ere used for direct introduction of values into the

W array. The element of the W array is first indicated by its number,

then the value to be introduced is listed. In the example, the bomb

volume is given in W(026). (This vlaue differs from that used by Good and

Scott, by the volume of platinum, which they apparently ignored). The

energy equivalent of the calorimeter in joules per degree is given in

W(07^-) o A fictitious density of air is given in W(567) to permit

masses (weight in vacuum) of the various substances in the bomb to be

used as given by Good and Scott.

Ti, Tf, and AT (corr) are introduced in W(078), W(079)^ an<^ W(o8o),

respectively.. Enthalpies of formation of carbon dioxide (g), and water (l)

are introduced in cal mol ^ in W(6^9) an^ W(650). W(6l2) is given

the value for the selected ratio of H^O/HF to be used in the calculations.

57
Atomic weights used by Good and Scott are introduced in W(55&) to

W(5<o3)« The number of F atoms in the compound of interest is placed

in W(206). Other quantities can be introduced at will for checking

or other purposes.

58
7 . Output Data

Table 3 is the format of the summary printout of the results of

the calculation. Some changes are made from the format suggested by

Shomate Q The number of decimal figures and the units of several

of the quantities are different,. Equations are given for the

idealized bomb reaction and for the reaction adjusted for hydrolysis

of any CF4. formed. Certain corresponding energy changes are

given. In the program these are calculated in joules first and then

converted to calories. Values are given at Th and at 298. 15°K, which in

this case are the same. The results give for the internal energy

change of the idealized reaction the value -35^-° 5^ heal mol which

may be compared with the value -35^» 5^ given by Good and Scott.

The calculations were compared with those illustrated by Good

and Scott at several stages in the development of the program. Only

minor differences occur, mostly due to rounding. The difference of

the value 35^» 5^- from 35^«51 heal mol ^ is apparently due to (l)

an error in the value for item 93 listed by Good and Scott, and ( 2 ) the use of a different solution energy for CO2 and a different

dilution energy for HF (aq). (Table 3 approximates the actual format).

59
PE

RFLUO

RO

PIPE

RID

INE

Pi H H 0 H H

53 53 53 53 25

Pd

W Pd Pd H O O CJ O S a . „ O 0 O 0 O Pi w Pd w Pd w p O p P PhO s

CO kn KN

C-~ 0 ON

-if O On VO

ON ON 0 CO

CO CO O ON O 0 • • 0 0 CM -if H

CM CM ow

CO 1 Pd KN 3

HI H -if 0 O O VO LTN VO CM \ Em . -if -if KN c0 ON CM -if C"— Pm CO Pd LTN HI LfN LTN VOH O

rHON tJ Oa <5U

KN1 V 0 0 -if X + CM *“3 CM

LfN

OJ

53

knw

HJ

rH

Pm 8O<>O

KNoC'-—

t" a KN

Pi

PdCOM

Pi§

Pd

00H

Pi

kn

PH

X!Pd oa zH

PM

PdOX

Pd53OMH<§Q

PdN

O- H 00 Pd VO CO ITS 3 KN KN ON VO w 0 9 KN KN KN 0 0 tjj 0 JEj 0 0 CM LfN KN KN KN

Pm • O in- *-) IN- N- CO -if 33 CM CM « -if -if -=t Pm O H rH rH O

KN t 1 1

KN + H

f- VO

rHO

CVI CO oo OJooON

rHOc

iHKN

CVJ oo

ir\ o < H 0 Q H O < f£3 rH Pd rH O

53 Pi 2 CO < O H |Y] Pd kD X D Pd KN

•<— P-j Em O CM

t=> Pd jgj < EM H CM • Pd H Pi Pd £d EM 25 O CM

HI <c 53 H Pd 5z Pd Pm Pj Pi H a <5 H O S M < 25 § EM < +

P-j Pi O Pd 00 > CO

00 Em tx] Em 53

M Fm Pd P-j 2! O to 52 Q O

Pm H Em O O O O' Pd 2 O O rd M Pd Pd M O 0 H EM H O O O O H < Cd O 53 EM t-l g O K M 0 fr~l M M O Pm r—4 O O H 2 2 HI Pi Pm O O M M 25 2 O Pd Pd O Ld 53 w O 0 O 3 O rH

PS

M Pm O 0 O Pd O

53oMHOcg

PiwQsQ§H

CO X X

Pi O O O

Pd Pd Pm a O Q

KN ^—N KN Pd rH X X rH H O a CO CO O O CO 53 ON Pd Pd ON H> vCM— Q Q CM 0 

KN KN <

Pd . rH rH Pd 2! O o s O O 2 CO CO jz M S ON ON S Em

JE CM OJ, Ch O O O <1

EM Pd Pd pM § O O O O

Pi Z Pi Pm

Pd pd O 3 ffl 35 §

Pd O O Pd COC l wH2 £3

2!

Pd

Pd

53w

pmPm

PdO

CJ ooH

PmEC

PmO

CO

JH

HISQ£

CMOoo

S!

60

1.0000000

2.2500000

115.4999990

5.0000000

10.9999999

.5000000

STANDARD

ENERGY

CHANGES

OF

ABOVE

REACTION

KJ/MOLEKCAL/M 0

LE

ENTHALPY

CHANGE

(298.

15

DEG

K)

-I857. 04-

445.84

INTERNAL

ENERGY

CHANGE

(298.

15

DEG

K)-

1865.10 “

445.77
Table 3

(continued)

ITS VO

CVJ IW OV VO 2

ITS i—1

CD CO 2 ON 2 CV1 lf\ rH CO

ON

C\J 2O2HsO

Pm2O 2o2<§o

PmPmO

t*CD22 2 £ 32 H22Q%QH H 2 2 9

CO ON CO CO CO CO CO CO CO Pd <1

-d* -=f pci 2 2 W 2 Pd Pd 3 OJ CD i 1 £ EJ £ !eJ £ S3 § CD & o O o O o O o O Ov 2 *~i *“> n “> 2 >q —

PM Pd 2 2 H O O H 2 O 2

KN 00 CVJ CVJ CO VO iH CVJ H CD Pd O r— It KN o VO C*- o CO CO 2 0 o o 0 0 o 0 2 2

t- VO CO on rH t- rH CO VO pg 2 Pm

~=t tNH rd CVJ vo c— 2 CVJ § Q PM o o ON 1 o o to OJ cvj CVJ CO t- CD Q CO 1 1 1 CO OV a w KN Ed <! i'—s o KN a pd o KN H 2 2 2CL. 1 fcrH O or t 88

Pm<

<5Q M CO 2 o CD E-M 2 2 1 2

Pd 2. O .H CD H 2 2 a 2 2 2 H 2 o 2 2 2 2 2 CD C— 2 2 O M to >m 2 2 2

>*

W CD 2 CD 2

Pd 2 <3 !2! 2 2 + 2 2 a < o 2 253 2 H 2 a CD 2 H 2 2

t-d O M H 2 2 CO O CD 2 Pd 2 2 b 2 CO 2 2 O

CO 2 H 2 a 2 • O 2 2

[HD to <3 2 2 H <3 KN 2 2

<3 Pm CD 2 O 2 KN O 2 2 2 2 2 2 o 2 2 2 2 2 2 2 » o 2 H H o o O O O O H • s CO <3 Pm Pm 2 2 2 2 2 <tj 2 a 2 2 o 2 >-r 2 2 2 2 2 O o O O O O 2 CVJ <3 2 2 2 2 M MM 2 2 O CVJ H H H PM H H 0 2 2 2 2

CD O CD CD CD CD 2 2- § 2 O O

Pd Pd

M 2 2 2 CD t

2 2 2 2 22 22 2 2 cvj H 2 H H 2 2 2 2 <d kn 2 2 2 2 o O o o o o a ko 2 a 2 2 o CD CD CD CD CD CD * a H H H

61
References

[1] C. H„ Shomate, "Computer Calculation of Combustion Bomb

Calorimetric Data, " U0 S. Naval Ordnance Test Station Technical

Report 327, China Lake, California, August, I963 .

[la] Co H. Shomate, "Fortran IV Computer Program for Reduction of

Heat of Combustion Calorimetric Data," Code 5052 (U0 S 0 Naval

Ordnance Test Station, China Lake, California, January I967 ).

[ 2 ] W. No Hubbard, D0 W» Scott, and Guy Waddington, "Standard

States and Corrections for Combustions in a Bomb at Constant

Volume," pp. 75“128° "Experimental Thermochemistry," F0 D0 Rossini, editor, (interscience Publishers, New York 1956)0

[ 3 ] w. Do Good and Dc W. Scott, "Combustion in a Bomb of Organic

Fluorine Compounds," pp» 15-39° "Experimental Thermochemistry,

Volume 2," H. A0 Skinner, editor .( Interscience Publishers, New York

1962)o

[4] Jo Do Cox and Ao J0 Head, "Solubility of Carbon Dioxide in

Hydrofluoric Acid Solutions," Trans» Faraday Soc» 58« 1839“^5

( 1962) 0

[5] D. W. Wagman, WQ H» Evans, V„ B0 Parker, I» Halow, S 0 Mo Bailey,

and R0 H0 Schumm0 "Selected Values of Chemical Thermodynamic

Properties," NBS Technical Note 270-1 (Ua S a Government Printing

Office, Washington, D0 C» 1967)0 (See also NBS Technical Note

270 -3 , 1968)0

£
Chapter h

STRUCTURE OF THE ALKALI HYDROXIDES . III. MICROWAVE SPECTRUM OF GASEOUS RbOH

David R. Lide, Jr. and Chi Matsumura

National Bureau of Standards, Washington, D. Co

The microwave spectrum of gaseous RbOH and RbOD have been studied

in a high temperature microwave spectrometer. The spectrum indicates a

linear or very near linear molecule with a large amplitude, low-frequency

bending vibration. The RbO bond length is 2,30 2. and the OH bond distance

o 85

is 0.97 A. The observed frequencies and their assignments for RbOH and

85 87 87

RbOD are given in Table 1. Similar data for RbOH and RbOD are

given in Table 2» The effective rotational constants and nuclear

85

quadrupole coupling constants for various vibrational states of RbOH

87

and RbOD are found in Table 3. Table 4 gives the values of q for

6 excited vibrational states involving v^. A fit of B^v^O to a power

85 87

series for RbOH and RbOD is given in Table 5. Variation of

rotational constants with v^ is shown in Table 6, while the structural

parameters found for the species is given in Table 7.

63
Table I 85 8 5 Observed frequencies in RbOH and RbOD

State

( 00

°

0 )

5/2 5/2

7/2 (7/2, 9/2)1

9/2 11/2 J 5/2 7/2

3/2 5/2

1/2 3/2

9/2 (7/2, 9/2)

}

85 RbOH

37744.8

37741.2

37738.3

37734.9

37728.6

8

5

RbOD

34324.6

34321.6

34317.9

34311.9

(01

L 0) 1+

5/2 3/2 ) 3/2 1/2 J 5/2 5/2 ] 9/2 11/2 J 7/2 (7/2, 9/2)

5/2 7/23

3/2 5/2J

9/2 (7/2, 9/2)

37600.7

37594.3

37591.3

37589.4

37584.7

34301.9

34299.0

34297.3

34292.3

(01

L 0) j&-

5/2 3/2?

3/2 l/2j

5/2 5/2 j 9/2 11/2

j

7/2 (7/2, 9/2)

5/2 7/21

3/2 5/2j

9/2 (7/2, 9/2)

37541.0

37534.9

37532.0

37530.6

37525.5

34 24 2 .

9

34240.1

34238.5

34233.5

( 02

°

0 )

7/2 (7/2, 9/2)7

9/2 11/2 J

5/2 7/2

3/2 5/2

1/2 3/2 j

37430.5

37417.1

34 242.8

34240.0

(34236.0)

( 02

20 )

1/2 (1/2, 3/2)

3/2 (1/2, 3/2, 5/2) 7

9/2 (7/2, 9/2, 11/2 )^y 5/2 (3/2, 5/2, 7/2)

7/2 (5/2, 7/2, 9/2)

37394.0

37385.2

37375.6

37372.2

34228.8

34220.

1

34210.4

34207.

(03

L 0) j£+

5/2 5/2

9/2 11/2

7/2 (7/2, 9/2)

5/2 7/2

^ 3/2 5/2 J

9/2 (7/2, 9/2)

J

37362.2

37358.9

37357.2

37352.5

34278.

3

34275.4

34273.5
Table 1 cont

(03

L 0) &.

5/2 5/2

9/2 11/2

7/2 (7/2, 9/2)

5/2 7/2

3/2 5/2

3

/2

J

37238.1

37235.0

37233.0

34152.2

34149.3

34147.8

(04

2 0)

1/2 (1/2, 3/2)

3/2 (1/2, 3/2, 5/2) 2 9/2 (7/2,9/2,11/2)

J

5/2 (3/2, 5/2, 7/2)

7/2 (5/2, 7/2, 9/2)

37179.4

37170.7

37160.9

37157.8

34189.2

34179.2

34174.8

( 10°0 )

7/2 (7/2, 9/2) ^ 9/2 11/2 X

3/2 5/2 > 1/2 3/2

9/2 7/2

9/2 9/2 5

37479.1

37472.7

37466.7

34095.4

34089.0

34082.9

( 1

1

L 0) 4+

5/2 5/2

9/2 11/2

7/2 (7/2, 9/2)

5/2 7/2

3/2 5/2

9/2 (7/2, 9/2)

5

2 ) >

37333.6

37330.8

37329.0

37324.1

34071.0

34068.2

34066.4

( 1

1

X 0) A5/2 5/2

9/2 11/2

7/2 (7/2, 9/2)

5/2 7/2

3/2 5/2

9/2 (7/2, 9/2)

}

.)}

37269.2

37266.4

37264.9

37260.0

34010.2

34007.5

34006.1

( 1

2

°0 )

( 12

2 0 )

7/2 (7/2, 9/2) |

9/2 11/2 ^

5/2 7/2

37164.5

1/2 (1/2, 3/2)

3/2 (1/2, 3/2, 5/2) ^

9/2 (7/2,9/2,11/2)

J

5/2 (3/2, 5/2, 7/2)

7/2 (5/2, 7/2, 9/2)

37140.7

37132.0

37122.3

37119.2

34010.5

34007.6

33995.2

33986.8

33977.3

33974.1

( 200 )

7/2 (7/2, 9/2) ) 9/2 11/2 J

5/2 7/2

3/2 5/2

1/2 3/2

9/2 (7/2, 9/2)

i

37216.9

37213.9

37210.8

37204.8

33866.8

33863.9

33860.7

65
Table II

8 V 87 Observed frequencies in RbOH and RbOD

J = 2 - 3

State

(00°0)

i F - F

7/2 9/2 )

5/2 7/2 )

3/2 5/2 ) 1/2 3/2 /

P

7 RbOH

37597.8

37595.6

87 RbOD

34188.4

34186.6

3/2 3/2 37455.1

7/2 9/2

^ 37450.8 34165.1

1 1/2 3/2 J

(01 0) £+ 5/2 7/2 ) 37448.7 34163.4

3/2 5/2 j

7/2 7/2 37444.0

7/2 9/2 > 37391.7 34106.9

i 1/2 3/2 J

(01 0) l- 5/2 7/2 ? 3/2 5/2 )

37389.7 34105.1

7/2 9/2 ^ 37287.5 34106.9

5/2 7/2 )

(02 0) 3/2 5/2 / 37285.6 34105.2

1/2 3/2 )

1/2 3/2 37246.8

2 7/2 (5/2, 7/2, 9/2) 37241.1 34082.5

(02 0) 3/2 (3/2, 5/2) 37238.3

5/2 (3/2,512,1/2) 37232.8 34074.2

7/2 9/2 ^ 37337.1 33960.8

n 5/2 7/2 J (10 0) 5/2 7/2 ) 33959.0

3/2 5/2 )

66
Table III

Effective rotational constants and nuclear quadrupole coupling constants

for various vibrational states of RbOH and RbOD.

State Bv ( 85

RbOH) Bv(

85 RbODi eqQ

00°0 E 6290.15 5720.77 -67.9

oi

L o TT 6260.55 5711.69 -67.6

02°0 E 6238.37 5707.08 (-67.9)

02

20 A 6230.13 5702.57 -67.4

03

L 0 TT 6216.43 5702.34 ( -67 .6)

04

2 0 A 6194.38 5697.42 -67

10°0 E 6246.45 5682.50 -65.9

1^0 TT 6216.70 5673.24 -67

1 2°0 E 6194.03 5668.37 (-66)

12

20 A 6187.95 5663.75 -66.3

20°0 E 6202.75 5644.40 -64.2

State Bv ( RbOH) Bv (RbOD) eqQ

00°0 E 6266.35 5698.13 -35

oi

1 o TT 6236.84 5689.32 -33

02°0 E 6214.63 5684.53 -31

02

20 A 6206.48 5680.02 -32

ooo

r-j E 6222.90 5660.18 (-33)

67
Table IV

^-Doubling constants

State q ( 85 RbOH) q ( 85

RbOD) q(

87 RbOH) q ( 87 RbOD)

(O^O) 9.87 9.82 9.85 9.70

(03

1 0) 10.33 10.51

10.73 10.12

68
Table V

2

Fit of BOv^ 0 to power series

85 RbOH 85 RbOD

i i

State calc BOv^ 0 Obs - calc calc BOv^ 0 Obs - calc

o 00 0 6290.10 0.05 5720.77 0.00

o

r— o < 6260.38 0.17 5711.70 -0.01

02°0 6238.57 o •ho o 5707.09 -0.01

02

2 0 6230.38 -0.25 5702.49 o00 O • 03

1 0 6216.48 -0.05 5702.34 0.00

04

20 6194.10 0.28 5697.45 -0.03

69
Table VI

Variation of rotational constants with V^

BOv^O B1 Vo

85RbOH

0° 47.70 43.70

l 1 43.85

2° 44.34

2

2 42.18

85 RbOD

0° 38.27 38.10

i 1 38.45

2° 38.71

2 2

38.82

87 RbOH

0° 43.45

87 RbOD

0° 37.95

70
Table VII

Structural parameters of Rubidium Hydroxide

From BOO^O From "B " e

r (RbO) 2.316 2.305

r (ON) 0.913 0.965

a) The first terms in equations (1) were used as "B " .

71
Chapter 5

MASS SPECTROMETRIC STUDY AT HIGH TEMPERATURES OF

THE Alg O3 -BeO SYSTEM

by

J. Efimenko

INTRODUCTION

Data have been obtained for the vapor species existing at high

temperatures for a number of selected compositions in the Alg Oq -BeO

system (Report No. 86 28, 9028, 9389). This report presents data and

calculated thermodynamic quantities for the eutectic mixture,

BeOiAl^Ok (94.2% Alg Q3), melting point 1890 ± 10°C, S. M. Lang,

C. L. Fillmore, and L. H. Maxwell, J. Res. NBS 48, 301 (1952). The

initial purpose of these investigations was to observe and study any

complex vapor species in this system. The following is a preliminary

report of these data.

EXPERIMENTAL

The procedure followed is similar to that used previously,

Report No. 9389. The mass spectrometer had been disassembled completely

and reassembled in the new laboratory previous to this experiment.

Before the eutectic mixture was placed in the instrument a blank run

was carried out. It was necessary to check whether contamination

from previously used materials was serious. In addition, a silver

calibration was performed in the same effusion cell before the experiment with this eutectic mixture was concluded.

RESULTS

Experimental data are shown in Table 1 and auxiliary data used

for computation in Table 2. Equilibria considered for this system are

the following:

(1) Al(g) + 0(g) + Be(g) j± AlOBe(g)

(2) 2Al(g) + 0(g) * Alj 0(g)

(3) A^ 0(g) + Be(g) si A10Be(g) + Al(g)

(5) Alg 0s •BeO(’t) c 2Al(g) + Be(g) + 40(g)

Equilibria constants corresponding to these reactions were computed

and are presented in Table 3. A second law treatment, (£nK vs l/T)

72
yielded enthalpies as shown in Table 4. For comparison, enthalpies for

the same equilibria, observed over the compound, Al^O^.BeO (80. 3% Alg 0^ )

,

are presented. On the basis of the reaction enthalpy for (1) this experiment indicates a value of AH§f “ -41 kcal/mol for the standard heat of

formation of AlOBe. The earlier experiments gave a value of -6.2 kcal/mol.

DISCUSSION

In the temperature range investigated, 2177 -256 2°K, the only

complex specie which appeared in addition to the species from the

individual reactants was AlOBe. At the higher end of the temperature

range, tungsten oxides appeared also but their intensities were minor

in comparison to the species Be

+

, 0

+

, Al+

. During the period that the data in Table 1 were obtained, two

shut-downs occurred. One was to replace the electron bombardment heat

ing filaments that failed and the second was to introduce a weighed

quantity of silver for a calibration. The data collected in any one

run are indicated by the sequence in the index number and the separate

runs by the tens series.

From Table 1 it is observed that there are 34 rows of data to

compute enthalpies for reactions 1 and 5, while only eight rows for

reactions 2 and 3. Since the specie of interest was AlOBe, more time

was spent accumulating data for reactions 1 and 5. One set of data,

index numbers 50-57, does not have a temperature cycle.

The computed equilibrium constants for reaction 1 show a rather

large scatter for check temperature points. Two factors can be

responsible for such a scatter. The effusion cell may have had a serious temperature gradient, before or after changing the bombardment

filaments and secondly, temperature equilibrium may not have been

established inside the effusion cell. Whenever a temperature cycle

was performed during a run, the down temperature data do not always

follow the same line as the up temperature data. Attainment of

constancy of ion intensity may not be a true indication of thermal

equilibrium after intentionally changing temperature. The equilibrium

constants for reactions 2 and 3 show much less scatter because no

temperature cycle was performed for the data, index numbers 50-57.

Since no composition analysis was made of the condensed phase

with time and temperature, reaction 5 will not be discussed here.

Using the eutectic composition BeOiAlgO^ (94.2% Alg Q3 ) gave a starting

composition with specific properties at equilibrium. Reaction 3,

which is not independent but is obtainable from combination of

reactions 1 and 2, is included as a check. These enthalpies need

to be re-examined because of the indicated discrepancies. Reaction 2

has been studied independently by other workers, reporting values

73
Z!sHo , -254 ± 7 and -243 ± 7 kcal/mol. A third law computation will be

made for the enthalpies of these reactions for analysis and comparison.

As pointed out previously, the data points for reactions 2 and 3 were

taken without a temperature cycle and include much fewer readings.

Data were obtained on two other eutectic compositions, BeOtAlgO^ (85.9%

Alg Cfe ) and BeOjAlgOfe (757* Al^O^), as well as another compound, BeO.ALg 0^

(80.3% Alg Q3 ) . This additional data will be analyzed for the same

gaseous equilibria.

Ik
Ion

Intensities

Over

Eutectic

BeOiAlgQs

(

94

. 27

>

Aig

Q

3)

co

4-1

1—1 o

>

CO0) •1—

I

4-) •r4CO6

a)

4-J

•i-l

O

r-F + <5

orH + .<!

0) PQOrH

+M

<J

+H°

03 03 CO CO co M< Mi b b b b b b b b

i-1 1—1 rH 1—1 i—i i—l 1—1 rH X X X X X X X X

00 4- CO 4- 4

- CM CM 0 CM r-l p-. CO 1—

1

CO 1—1 rH

03 C0

03 b b CO CO M< b

^ rH b b b

M

1 M1 i-l X X rH iH iH b b

i—i i—i x m m X X X • • X X

00 co p- co m 4- CM r-l MO CO iH rH ON ON

M M

CO CO M* M U U M* M< Mi M* Mi C0 Mi M< M< b b b b b 1—1 rH

Mib

b b b b b b b bb i—l r—

!

rH r—l iH 1—1 1—1 rH rH i—l rH i—l rH rH X X rH X X X X X

m m X

X X X X X X X X X

00 rH i—l m • • CM m m 0 r-« CO 0

rH rH m CO i—i 4

- co NO p^ 4- m 4- ON i-M m co CM

03 03 CO

iH |H rH b b CO b CO co CO CO co 03 03 03 03 CO b b b

i—i r—i br—i b b b b b b b b b b

iH rH H X X rH X rH rH iH rH 1—1 rH tH 1—1 rH rH X X X m CO X m X X X X X X X X X X

CM CM Csl b nO CM ON 1—1 rH co p'. rH CO 0 rH

4" CM rH nO CM co CO CM vD NO CM vO CM rH

03 03

03 03 b w n n ^ 't b to co co 6b H bbbbb t?bbbbbbbbbbbb H bbb 1—I

1—I X 1—I 1—I r—I 1—I r—I O 1—I 1—I

1—I 1—t r—I 1—I r—I 1—I 1—I t—I r—I

1—I X 1—I

1—I r—

I

1—

I

XXnOXXXXX • XXXXXXXXXXXX-4 XXX

X

O'COiOlHCOCOrNH HHCOiO!NcOvOOOiOHcoMH<fa\0 <j" cm ,

1 00 co 1—1 lo l/') 00 in 00 on co co rH p-~ >—i vo 4" i—i co i—i

,—

i

M CO M

co CO CO CO CO M M* b M* M* M* b CO C0 Mi M M< M* CO CO b

a) b b b b b b b

rH b b b brH b b b b b b b b b b

rH b

+ M rH rH rH H rH r—l rH X rH rH r—i iH X rH 1—1 i—l 1—1 r—l rH 1—1 i—

1

rH rH X rH H

X X X X X X X m X X X X 4- X X X X X X X X X X m X

ON p^ CO 00 NO 4

- i—i NO CO p>. i—i m 4- CO 0 p* 0 NO m 00 m ON in 4" ON NO 4

" CM iH NO 4" CO CM m I—l CM I—

1

m CM CO NO CO CM co iH 00 m

O0 O in m O 0 m m 0 O O CM 0 0 O m 0 O O 0 0 O m 0 00 0

ON co 00 CO 00 ON m m NO Mf ON ON 0 m 00 CO 00 NO CM 00 m m ON CM 00

•s r—l 1—1 0 O ON 00 00 00 00 00 00 00 0 0 ON ON 00 00 ON 00 00 0 ON ON 00 H CM CM CM CM i—l r—i 1—1 rH I—1 1—

1

i—l rH CM CM 1—1 i—i 1—

1

1—

1

i—l i—i r—l CM rH 1—1 i—i

X

OJ . O NO in 4

- CO CM r—l 0 0 1—1 CM co <± m NO Ps 00 0 r—l CM CO O iH CM co C SZ5 m m m m m m m m I—l 1—

I

i—l rH 1—1 rH r—l 1—1 i—i CM CM CM CM CO CO CO CO

75
TABLE

1

(continued)

M< CO to •<* b b b b b b b b b

iH H lH rH rH i—

1

I—

1

i—

1

rH X X X X X X X X X

CM CM oo vO o CM in 1^ rH lH CM rH Ov LO CM rH

03b 03 rH 03 03 03 03 03 03 rH b b b b b b b b

X rH iH rH i—

i

rH rH rH rH X X X X X X X X

iH r». m r- CM rH CO VO CTv rH m CM rH VO CM 00

CO co 03 03 03 co 00 eo PO b b b b b b b b b

rH rH rH iH rH iH rH rH rH X X X X X X X X X

<t iH r^> <t vO o CO

CM ON vO CO r—

1

00 CO vO i—i

CD 03 to CD CD CD to M< b b b b b b b b b

rH rH H rH rH rH rH rH rH X X X X X X X X X

Ov On o Ov vO co co CM m rH iH vO CM r—

i

CM

in m O O o O m in O

co co O uo oo CM CM ov o CM rH o o CTv O OV

rH CM CM CsJ CM CM rH CM »H

oo r^» vO m CO CM iH o

Mt

76
TABLE 2

Auxiliary Data

Sensitivity, S

Ag

Temp. - Silver Calib.

Window + Prism Transmissivity

1.7796 X 10“ 8 amp/mmHg

1305K

1.40 X lCr 5 !^ 1

Specie

Ionization

Cross Section

cri (1)

Multiplier

Sensitivity

Yi (2)

Ag 34.8 296

Be 6.3 276

0 3.3 288

A1 15.4 292

Alg 0 34.1 226

AlOBe 25.0 93

(1) J. W. Otvos and D. P. Stevenson, J. Am. Chem. Soc.

78, 546-551 (1956).

(2) Experimental values, author.

77
No

57

56

55

54

53

52

51

50

10

11

12

13

14

15

16

17

18

20

21

22

23

30

31

32

33

48

47

46

45

44

43

TABLE 3

Equilibria Constants

K* subscripts refer to the reactions listed below

1/T, °K h Ka Kb X IO20

3.9201 1.2730 3.6402 3.4971 5.7040 X IQ- 30

4.0128 4.0242 1.2165 3.3082 9.5881 X 1

0” 3 2

4.1009 1.1166 3.9963 2.7941 1.5154 X 10- 33

4.2022 3.7407 1.4808 2.5261 1.5368 X icr 35

4.2985 1.5657 6.6793 2.3441 7.3905 X icr 38

4.4725 1.3175 6.0730 2.1694 2.4400 X icr41

4.5592 7.9974 2.4020 3.3294 1.1349 X 10-4S

4.5703 1.1798 1.6978 6.9490 1.0738 X io- 43

4.5482 1.3564 4.1156 X 10“43

4.5926 3.0777 1.5066 X icr 44

4.4789 4.2548 1.8209 X 10“ 42

4.4832 3.2166 2.9582 X 10“ 42

4.2595 1.1251 4.9912 X 10" 38

4.1648 2.2541 8.5291 X icr 36

4.2887 1.2952 1.8948 X icr 38

4.3993 6.5663 9.4411 X 10“ 41

4.5047 4.4072 3.5974 X icr43

4.5482 1.1973 1.4185 X icr 44

4.4200 7.9299 1.1580 X io-41

4.5047 4.4311 1.6163 X io- 43

4.5703 9.0211 9.7115 X icr 45

4.1555 3.8737 1.7242 X IO" 34

4.2789 1.9521 6.4258 X IO- 39

4.4034 1.8653 4.0287 X icr 40

4.5047 9.1351 3.3718 X icr 42

4.3890 1.3427 6.5356 X 10“ 40

4.1928 8.5192 1.0185 X Iq-36

3.9037 1.0857 3.5567 X 10“ 29

3.9871 3.7652 3.3823 X icr 33

4.1099 1.6873 1.6897 X icr 35

4.1834 6.7253 1.4244 X IO" 35

4.3084 4.2802 2.6880 X IO" 38

4.2116 1.17 28 2.6290 X IO" 36

4.4200 1.8497 1.1650 X 10“ 38

ai + o + :Be AlOBe, Kjl 2A1 + 0 « Ala O, Kg

Alg O + Be AlOBe + Al, *9

AlgOg .BeO {l) - Be + 2A1 + 40, Kg

78
TABLE 4

Reaction Enthalpies

Results from eutectic BeOiAlgO^ (94.2 wgt % Alg Q3 , melting point

1890 ± 10°C)

Reaction At§ 350 , kcal/mol 4$^, kcal/mol

( 1 )

( 2 ) (3)

(5)

-260 -254

-262 -256

+1.82 +1.89

+980

Results* from compound BeO.AlgO^ (80.3 wgt % Alg Q3 , melting point

1870 ± 10°C)

Reaction AH^ 3 50 , kcal/mol AR§ , kcal/mol

(1)

( 2 ) (3)

(5)

-222 ± 4.6 -216

-257 ± 6 -252

+35.5 ± 4 +36.2

+952 ± 71

* From Report No. 9028.

79
Chapter 6

THE ENTHALPY OF TUNGSTEN FROM 1100 TO 2600°K

E. D. West and S. Ishihara

The high-temperature enthalpy of tungsten is important not only

because of its use in high-temperature engineering applications but

also because of its use as a container material in the high -temperature

enthalpy measurements of other materials and its possible use as a reference material for these measurements to permit a check on the

capabilities of various laboratories.

In earlier work in this program [1,2], tungsten was used as a container for liquid Aj^O^ and liquid BeO’A^O^. Revised results for

the latter are reported in a subsequent chapter in this report.

The work reported in this chapter was carried out as part of a National Bureau of Standards program related to work done for AFOSR.

Method and Apparatus

The method and apparatus have been described briefly [1,2,3]*

Essentially, the apparatus consists of a furnace, in which a specimen

in a capsule is held at various high temperatures, and an adiabatic

calorimeter, operating near room temperature, which measures the heat

given up when the hot specimen is lifted into it. Heat lost by the

container in the transfer process is accounted for by separate

experiments with the empty capsule. If all the heat lost comes from

the capsule wall in both experiments, it is accounted for when the

difference in heats is ascribed to the specimen.

The temperature in the furnace is measured by a Leeds & Northrup

automatic photoelectric pyrometer sighted on the bottom of the capsule.

The output signal from the pyrometer is used in a control loop to

maintain a selected constant temperature while the capsule is in the

furnace. Some improvements have been made in the pyrometry since the

earlier report [1]. Frequent balancing of the integrator circuit has

apparently improved the precision of the temperature measurement. Reported temperatures are based on a calibration made by the NBS Radiation Thermometry Section in 1967* The conditions of this calibration

are closer to the conditions of use than those of the 1965 calibration

although the maximum difference between the two is 0.2$ at 1108°K.

Four spot checks between these two calibrations do not show any

consistent trend. They differ from the 1967 calibration by -0.16,

-0.95, +0*31 and +0.66°K.

80
At high temperatures , there is considerable risk of contamination or mechanical damage to both specimen and container. With

tungsten we found it helpful to use a smaller specimen for higher

temperatures to reduce breakage of the suspension wire. To minimize the risk and permit this flexibility, we use a method which

yields in one day*s work all the information required for the

calculation of the enthalpy at the operating temperature for that

day. Usually four experiments are made at the same temperature in

a day —two with the capsule alone and two with the capsule plus

specimen. For some higher temperatures, only two experiments are

made because of the time required for additional weighing. Weights

of the capsule and the specimen can be made after each experiment to

check for contamination or vaporization. Allowance for variations

in the heat for the capsule can be made by correlating weight gains

and observed heats for the empty capsule.

A principal advantage of this method is that loss of a capsule

or container on one day does not invalidate data taken previously as would be the case if all the data were obtained for the empty capsule

before any measurements were made with the specimen. In this case,

loss of the capsule might mean loss of the data taken with it. In

experiments at 2700°K, a tungsten capsule developed a crack which

allowed contamination of specimen D with carbon from the furnace

atmosphere, but experiments at lower temperatures were not affected.

Another advantage of the method is that it facilitates inter

comparison of different specimens under nearly identical conditions.

At 1613 °K, for example, two different specimens were used the same

day.

Ifete rials

Four specimens were used in this work. These are described

below with the same designations used in table 1. All machining was

done by grinding with aluminum oxide wheels.

Specimen ACommercial "pure”, nominally 99 * 95% tungsten.

Spectroc hemic al analysis of another piece of the same rod for 51

elements found a maximum of 0.01$ impurity. Surface was cleaned by

rinsing in carbon tetrachloride. Weight (corrected for buoyancy)

23.013U g, constant to 0,2 mg, which is about the limit of the

balance used.

Specimen B : Triple zone -refined tungsten nominally 99 . 999%

tungsten, in the form of one-eighth inch diameter rods. The rods were

cut to length, but not otherwise machined. The surface was treated

with one part I4

. 8$ HF and two parts concentrated HtJO^ for one minute.

The weight was 13*3911 g constant ± within 0.2 mg.

81
Specimen C : Same as A but surface treated with one part HF and

three parts HNO^ . Weight I3.8I4.82 g constant within 0.2 mg until it

gained 0.6 mg in the experiment at 2lt03°K.

Specimen D : Same as C, except weight 10.6807 g. The specimen

gained O.I4. mg at 2l4.50°K, O.I4. and 2.9 mg at 2600, 15.5 mg at 2700°K

and 20.6 mg at 2800°K. Analysis in a carbon-hydrogen combustion

train found 0.7U$ carbon in a sample 1 mm long cut from the ends of

the specimen. A second sample 2 mm long adjacent to the first showed

0.12$ carbon. The analysis indicates that carbon vapor reached the

specimen through the crack in the capsule wall near one end.

The atomic weight used for tungsten was 183.85.

Results

The corrected experimental data for the enthalpy of tungsten are

shown in table 1. Three capsules and four specimens were used, as indicated in the last column. The specimens are described above.

The temperature in the first column has been corrected for the

loss of radiation in a prism in the optical path. Corrections made

for variation in room temperature in earlier work [l] are no longer

necessary

.

The quantity of heat in the second column includes corrections

for the enthalpy of the capsule and specimen between the actual final

calorimeter temperature and 298.15°K. Data required for this correction are taken from Stull and Sinke [U] • Corrections made in the earlier

work [1] for small variations in the furnace temperature are no longer

required. The enthalpy calculated from one experiment with the capsule

and one with the capsule and specimen are shown in the third column.

The data for the enthalpy of tungsten in kilojoules per gramatomic weight are represented by the equation

H

T'

H298 1$ “ '7- 113 + (23-Oiil)lO‘3 T + (2.9836)10‘°T

2

- ( .82203 )l

O' 9

T

3

+ (.21967 )10’12 9* kj/gaw (1)

The standard deviation is 0.17$. Deviations are shown in the fourth

column of table 1.

The table contains data for very pure tungsten (sample B) at

four temperatures. The percentage deviations are -0.03, -0.20, +0.09,

-0.23, and -0.12. We regard these differences as insignificant and

the data for sample B have been used in obtaining equation (l).

82
One point at 2353°K was omitted in determining equation (l) because it differs by more than three times the standard deviation from

the corresponding value from equation (l), although the experiment

does not have any apparent defect.

Equation (l) was obtained by the method of least squares, minimizing the sum of the squares of the percentage deviations. This procedure is preferable to working with the deviations themselves because

the uncertainty in temperature measurements increases with the

temperature. Such a procedure would tend to give too much weight to

the experiments at high temperatures.

Discussion

Kirillin, et al. [5] summarize the measurements irmde before 1963,

including their own. They represent the data of several observers

with two smoothing equations, one for the range from 250 to 385 °K and

one from 385 to 3100 °K. The maximum difference between their equation

and equation (1) is 0.59% at 2050®K. For their data for the range

1275 to 2600 °K, the standard deviation is 0.U6%. From the deviation

plot given [5], it appears that the data in this range are more precise

than the standard deviation indicates. For this reason, we have obtained

equation (2) for the enthalpy in kilojoules/gram-atomic weight which

fits their data for the range 630 to 3093 °K with a standard deviation

of 0.33%:

h

t'

H

298.15

= -3 * 85U + (25.8U8)10‘

3

t + (0.72U05)10'

6

t

2

+ (. 30599 )10"9

T

3 - .68886 £nT kj/gaw (2)

The difference between equations (1 ) and (2) is +0.15% at U00°K, decreasing to -,22% at 1900°K, then increasing to +0.29% at 2500 and

0.51% at 2600°K.

The agreement between the two equations is quite good except at

the highest temperature . That agreement is better between equations

(l) and (2) than between equation (l) and the equation of Kirillin,

et al. [5] indicated that the latter may have given too much weight to

older data in the temperature range below 1100°K.

Since tungsten is used as a container for liquid oxides, the data

for the enthalpy of tungsten affect the liquid data obtained for A^2^3

and BeO’Ai^O^ previously reported [1,2]. Revisions of those data are presented in subsequent chapters.

83
References

[1] E. D. West and S. Ishihara, NBS Report 9028 to AFOSR,

1 January 1966, p. 71*

[2] S. Ishihara and E. D. West, NBS Report 9601 to AFOSR,

1 July 1967, p. 55.

[3] E. D. West and S. Ishihara in "Advances in Thermophysical

Properties at High Temperatures and Pressures," Am. Soc . Mech.

Engr . 1965 , P • 1U6

.

[k] D. R. Stull and G. C. Sinke, Thermodynamic Properties of the

Elements, Am. Chem. Soc., Washington, D.C. (1956).

[5] V. A. Kirillin, A. E. Sheindlin, V. Ya. Chekhovskoi, and

V. A. Petrov, J. Phys . Chem. USSR 37, 1212, 1963,

translated from Zh. Fiz Khim 37_, 22^9 (1963).

[6] V. Ya. Chekhovskoi, B. Ya. Shumyatskii, and K. A. Yakimovich,

Inzh. Fiz. Zh. Akad. Nauk Belorussk SSR 5, 13 (1962).

8U
Table

Furn . temp .

Date of run

1108.8

3-16-66

1183.8

2 -23-66

1183.8

2-16-66

1333.6

2 -lit -66

Hi05.

9

3-7-66

151U.3

2 -11-66

1613.

2

3

-18-66

1726.8

2 -9 -66

1815.

7

3

-11-66

L. Experimental Data for the Enthalpy of Tungsten

a

Ifeat to Calorim- hT _h298.15 % Deviations Specimen

eter at 298.l5°K kJoules/at .wt. Obs -Calc

.

and Capsule

Joules from eq (l) Material

1+599-1+

1933-3

21.299 .02 A, Mb

1933-3

1+599.6 21.301 .03 k, Mo

2129.6

5056.6 23.383 -.11 A, Mo

5055.9

2125.2

23.1+13 .02 A, Mo

2121 .

h

5050.9 23 .1+0

3

-.03 A, Mo

5052.0

2119.7

23.1+26 .07 A, Mo

2508.3

5967.8 27.638 -.09 A, Mo

5970.0

2510.6

27.637 -.09 A, Mo

61127.7

2705.1

2706.7

29.739 -.03 A, Mo

1+872.9 29.71+1 -.03 B, Mo

3001.6

7136.7 33.035 .35 A, Mo

711+2.9

3008.8

33.027 .33 A, Mo

7758.5 35.71+7 -.30 A, Mo

3283.9

3285.9

5892.3 35.781+ -.20 B, Mo

3605 .1+ 8529.1 39.335 .12 A, Mo

8531.2

3607.2

39-337 .12 A, Mo

9127.9

3860.3

1+2.082 .13 A, Me

3866 .2

9109.9 1+1.891 -.32 A, Mo

85
Table 1 (Cont’d)

Furn. temp.°K Heat to Calorim- HJ-H298.15 % Deviations Specimen

Date of run

eter at 298.15°K kjoules/at .wt. Obs-Calc

.

and Capsule

Joules from eq (l) Ifeterial

1915.4 4166.9

3-14-66 9812.0 45-097 -.10 A, Mo

9827.3

4163-8

45.245 .23 A, Mo

1998.1 4400.6

3-21-66 7883.8 47.821 .09 B, W(l)

7893.2

4421.4

47.665 -.23 B, W(l)

2107 .4 8615.3 51.268 -.12 B, W(l)

3-23-66 ir753 • 7

4764.4

8502.1 51.317 -.03 C, W(l)

2107.5 8874.4 51.155 -.35 C, W(l)

4-18-66 5021.0

5023.9

8891.8 51.347 -.02 C, W(l)

2210.0 5059-4

3-31-66 9186.0 54.785 .08 C, W(l)

9215.1

5095.0

54.700 -.08 c, W(l)

2209.1 5078.5

4-4-66 9215.6 54.924 .38 C, W(l)

(Slow lift 9232.3 54.825 .20 C, W(l)

time

)

5102 .6

2267.7 3473.0

4-14-66 6770.5 56.761 .11 D, W(2)

2300.8 9803.9 57-783 -.09 C, W(l)

4-6-66 5451.5

2U03.3 5944.5

4-8-66 10569.2 61.394 -.02 C. W(l)

86
Table 1 (Cont‘d)

Furn. temp.°K ffeat to Calorim- Ht-iw ^Deviations

,Iwt. Obs-Calc.

from eq (l)

Specimen

Date of run

eter at 298.l5°K kJoules/at and Capsule

Material

Joules

21*60.8 U101 .U

1* -2 1-66 7799.1 63 .61*9 .30 D, W(2

)

2503.1 771*1.8 61*. 671 -.U8 D, ¥(2)

U-12-66 3981*. 8

2601* .1* 5167.1

U-25-66 9171.6 68.931 .31 D, W(2

)

8896.6

1*912.7

68.577 -.20 D, W(2)

2353.11* 7126.2 59.232 -.70 D, W(2)

1*—15—66 3685.1

Atomic wt. of tungsten 183.85.

This point was given zero weight for determining the smoothed curve.

87
Chapter 7

THE ENTHALPY OF SOLID AND LIQUID R3 OAA2 O3

FROM 1200° TO 2l|00°K - REVISION

S. Ishihara and E. D. West

The data presented"'" for the enthalpy of solid and liquid BeO'A^Os

Ishihara and West, NBS Report 9601 to the AFOSR, 1 July 1967.

have been revised slightly as a result of a calibration of the automatic

pyrometer carried out following completion of the measurements and also

as a result of new data for the enthalpy of tungsten, which affects only

the data for the liquid. The revisions affect the enthalpy relative to

298.15°K by less than 0.1$. They are therefore probably not important

in engineering calculations, but may be useful in checks of consistency

of thermodynamic data.

The enthalpy of solid BeO'A^O^ from 1180 to 21l4-3°K relative to

29 8.15 °K is given by the equation:

Up - ^2 <j8 ,i5

“ - (0.255187 )T + (3.U6055)10'V - (l.UUl23)lcf 7

t

3

+ (2 .U3189 )10

_11

T^ + 72.2028 4nT - 362 .U33 kJ/M (1)

The enthalpy calculated from equation (l) will be approximately 0.05$

lower than that calculated from the earlier equation.

x" With the increased precision from the new calibration, an additional constant is

•warranted (F test at 95$ confidence level). ^ The constants in

M. G. Natrella, Experimental Statistics NBS Handbook 91 (U.S. Dept,

of Commerce , 1963 )

.

equation (1) are therefore quite different from those in the earlier

equation, but the difference in enthalpy calculated is small.

Equation (l) fits the data with a standard deviation for an individual

measurement of 0.16$, which is very slightly smaller than that given

earlier

.

In the earlier report a minus sign was omitted for the logarithmic

term.

88
The enthalpy of liquid BeOAJ^C^ has been corrected for new data

for tungsten, which was used as a container material, and also for

the new pyrometer calibration. The enthalpy for the range 21U3 to

2lj00 o K is given by the equation:

H

T

-H29ai5

= 1299 - (0.9376)T + (0.2637 )10'3 T

2 kJ/M (2)

The enthalpy calculated from (2) will differ by less than 0.1% from

the enthalpy calculated by the earlier equation. The root -mean -square

deviation from equation (2) for a single determination consisting of

three experiments is 0.03%.

The heat of fusion at 2114-3 °K calculated from the difference

between equations (1) and (2) is 172.3 kj/mole, lower by 1.5 kj/mole

than the value reported earlier . This value depends slightly on the

temperature taken for the melting point and Increases O.OI4 kj/mole

for each degree decrease in the melting point.

89
Chapter 8

THE STATUS OF THE THERMOCHEMICAL DATA ON SOME Mg COMPOUNDS

by Vivian B. Parker

I Introduction

As part of the revision of NBS Circular 500 "Selected Values of

Chemical Thermodynamic Properties", we have completed a review of the

available data on all magnesium compounds. We present here a summary

of values selected from this review for substances pertinent to the

Light Element Thermodynamics Program. We are including also a brief

discussion of the sources from which these values have been calculated.

It is hoped that this report will indicate where additional research

is required. We will appreciate it if data that have been overlooked

or errors in the values are brought to our attention before the final

tables are published.

All auxiliary data and constants used in the calculations are given

in NBS Technical Note 270-3 [1]. All values of AHf° and AGf° are in

kcal/mol for the molecular formula written and at 298°K, unless otherwise specified. Caution should be exercised if these values must be

combined with data taken from other compilations or sources, in order

to avoid errors caused by a lack of consistency between the tables.

II Discussion of Data

Mg(c) This is taken as the standard state. The thermal functions

were taken from the evaluation of Hultgren et al. [2,3].

Mg(g) The AH0 (sub 1 ) =35.3 kcal has been taken from the tabulations of Hultgren et al. [2,3], as have the thermal functions of the

ideal monatomic gas. Hultgren et al. [3] revised their original

selection of 35.3 to 35.0 kcal. We prefer 35.3.

90
Mg" (g) The successive ionization energies were taken from Moore [4].

°-r Mg^ (aq , std. state, m - 1) See ilgCl^Caq)^ Mg (CIO^) (aq, std. state,

m = 1) and Mg (NO^)

^ (aq)

.

Let us first consider Adf° from the aqueous MgCl^ system. The values

given in Table II were corrected to AHf°. Representative values from

the MgCl^* 611^0 system are: Samoilov -191.17 kcal; Voskresenskaya and

Ponomareva -191.10; Thomsen -191.42; Mishchenko and Yakovlev -191.17. From

the MgCl^ ^H^OCc) and MgCl^ * 2^0(0) systems we obtain from Thomsen's

measurements -191.77 and -191.20. From MgCl^Cc) we obtain: Mishchenko

and Yakovlev -190.92; Mishchenko et al. -191.17; Thomsen -190.28. From

Richards et al. we obtain -189.56. A tentative "best" value for AHf°

MgCl^ is -191.22 kcal with AHf 0 Mg

2

'(aq, std. state, m = 1) = -111.32

kcal

.

For MgCClO^)^ AHf° is -173.63 kcal from which we obtain AHf° Mg

2* = -111.81 kcal.

From the Mg (NO ) system, we obtain for AHf°: Pickering -210.67;

Thomsen -211.00; Ewing et al. -210.57 and -210.72. These result in a AHf 0 = -210.74 and AHf ° Mg

2* = -111.62 kcal.

2+

We have selected as "best" value for AHf° Mg -111.58 kcal.

From the solubilities given by Linke [5] and the activity coefficients and osmotic coefficients given by Robinson and Stokes [6] we

obtain A3°soln MgCl^ • 61120(c) = -6.09 kcal and A3°soln MgSO^ -bl^CKc)

(metastable at 25 °C) = +2.18 kcal. Combined with the appropriate

heat of solution data we obtain AS°soln = +6.70 e.u. and -10.64 e.u.,

2+

respectively. These result in S° Mg = -33.1 and -32.5 e.u. We

have selected S° = -33.0, with A3f° Mg

2 ' = -108.7 kcal.

MgO(macrocrystal) and MgO(microcrystal)

The thermal functions for the macrocrystal were taken from the

tabulation of the Dow Chemical Co. [7]; those for the microcrystal

from the evaluation of Furukawa et al. [8].

There are many determinations for AHf ° MgO(c) ; however, very few

of them distinguish between the macro and micro crystal forms. The

following values were reported without any indication which form was

91
obtained or the percent of each obtained in the direct combustion of

Mg(c); Muthman and Weiss [9], -143.0 kcal; Moose and Paar [10] -146.1;

von Wartenberg [11] -143.9; Rogers [12] -146.4; Vorob'ev and Skuratov

[13] -143.9; Shchukarev et al. [14] -143.23; Holley and Ilubcr [15]

-143.65 kcal.

Shomate and Huffman [16] measured the heats of solution of Mg(c)

and MgO in aqueous HC1, from which we obtain Mg(c) + H^OCliq) -* MgO(c)

+ ^(g), AH 0 = -75.494 kcal and AHf° = -143.81. No mention is made of

the crystal size of MgO; however, the MgO used was made from igniting

Mg (OH) ^ (c) at high temperature; the macro crystal form is usually

obtained by this method. We are therefore adopting this value as the

AHf° of the macro form. It is the only definite one for all macro

MgO(c)

.

Giauque [17] showed that finely divided MgO prepared from the reduction of MgCOH)^ at low temperature gives a different S° and AH soln

in HC1. He reported AH° = 0.89 kcal for MgO(macro) -* MgO(micro).

This results in AHf° = -142.92 kcal.

MgO(g) Brewer and Porter [18] from their vapor pressure measurements

have shown that the solid vaporizes mainly into molecular species.

They gave spectroscopic evidence that the ^Z electronic state is not

3

the principal vaporizing species. From their measurements and a Z

ground state we obtain a 3rd law AH°subl = 129 kcal, and a AHf° = -15

kcal. From Alexander et al.'s [19] H^OCg) transpiration study we obtain a 2nd law AHf° = -4 and a 3rd law AHf° = +5 kcal. Altman's [20]

Knudsen effusion and 0

? transpiration studies indicate that MgO(g) is

of little importance at 2000°K (in contrast to Brewer and Porter) but

from the experiments in which 0

9 (g) is passed over MgO(c) the 3rd law

AH°subl = 162 kcal and AHf° = +18 kcal. From Porter et al. [21] we

obtain AH°subl > 148.6 and AHf° >4.8 kcal.

Bulewicz and Sugden [22] and Veits et al. [23] reported D° = 98

3 1

U

and 100 kcal for a Z and Z ground state, respectively. These re3 suit in AHf° = -4 kcal and -2 kcal (corrected to a Z ground state).

Drowart et al. [24] used the Knudsen effusion-mass spectrometer

technique to determine relative ion intensities and enthalpies for the

92
reactions :.gO(g) 0(g) - Kg, (a) + 09 (g), r.vul MgO(g) + W0

2 (g) -* Mg(g) +

wo

3 (g). We obtain, corrected for a v ground state, Allf 0 - +12 and +20

lccal from the two reactions.

As is evident , the values are very discordant. We are taking AHf° - +4 keal. The uncertainty is large , ±20 lccal.

Brewer and Trajmor [25] feel that for the purposes of high temperature calculations, the most reliable calculations are obtained by the

3 assumption of a tt ground state for MgO(g). This would increase AHf°

approximately 3 keal.

The thermal functions used in the calculations were obtained from

the Dow Chemical Co. [7].

KgH^Cc) The thermal functions were obtained from the Dow Chemical Co.

[26] which also cites the references and values obtained for AHf°. We

have taken AHf° = -18.0 keal.

In addition Pepekin et al. [27] reported AH° = -190.4 keal for the

oxidation of Mg^ to Mg0(c) + H^OQiq). This results in AHf° = -21.7

keal

.

+

Mg OH (aq , std. state, m = 1) From Sillen and Martell [28] we obtain

logK = 2.58 for Mg^

+

(aq) + OH -» MgOH

+

. Hostetler's [29] value is

in agreement.

MgCOlO^Cc) The thermal functions were obtained from the Dow Chemical

Co. [30].

Wells and Taylor [31] measured the heats of solution of Mg (OH)

2

(c)

and MgO(macro) in 2N HC1. We obtain for Mg0(c) + H^OCliq) -* Mg(0K)^(c),

AH° = -9.02 keal and AHf° = -221.15 lccal. Similarly, from Taylor and

Wells' [32] measurements, we obtain AH° = -9.07, using macro MgO and

brucite (AHf° = -221.20) and -8.83 lccal using macro MgO and synthetic

MgCOH)^ (AHf° = -220.96 keal). From Giauque and Archibald [33] we

obtain AH° = -9.735 keal, using micro MgO, and AHf° = -220.97. Torgeson and Sahama [34] measured AH = -26.95 lccal for the solution of

synthetic MgCOH)^ in IN KC1. Using the results of Shomate and

93
Huffman [16] on the solution of macro MgO, we obtain AH° - -8.84 kcal

for the formation of Kg(OU) 9 from macro MgO and H0 0(liq) and AHf° = -220.97 kcal. From Roth and Chall's [ 35 ] measurements we obtain AH° » -7.96 kcal and AHf° = -220.1 kcal (this is assuming macro MgO(c) is

used). We have selected a "best" value of -220.97 kcal.

Giauque and Archibald’s decomposition pressure measurements are

in agreement with this value. The Dow Chemical Co. [30] cites other

decomposition vapor pressure measurements.

Mg(0H)

2

ppt. From Thomsen’s [36] measurements we obtain AH = 31.3

kcal for MgS0

4

(400 ^0) + 2H

2 0(liq) - Mg(0H)

2

ppt. + H

2

S0

4 (400 H O),

and 0.7 kcal for MgS0

4

(400 ^0) + 2K01I(200 H

2 0) - K2

S0

4 (800 HO) +

Mg(0H)

2

ppt. These reactions result in AEf° = -220.5 and -219.8

kcal. From Berthe lot’s [37] measurements we have AH = 0.4 kcal for

MgS0

4 (400 H

2

0) + 2Na OH(200 ^0) - Mg(0H)

2

ppt. + Na

2

S 0

4

(800 H

2 0) and

AH = 1.5 kcal for MgCl

2

(400 HO) + 2NaOH(200 H

2 0) - Mg(0H)

2ppt. +

2NaCl (400 HO). AHf ° , then, is -220.1 and -219.5 kcal.

Mg(OH)

2 (aq,std. state, m = 1) The values were obtained from the

ions

.

Mg(OH) (g) Alexander et al. [19] determined the Kp’s (from 1780°K

to 2010°K by the transpiration method) of the reaction MgO(c) +

H

2 0(g) -> Mg (Oil) (g) . AH^

9 qo°k = 66.8 kcal from which we obtain

AH° = 67.6 kcal and AHf ° = -134 kcal.

The values of H - H QQ used in correcting AH to 298 °K were taken

Zyo

from the estimated functions of the Dow Chemical Co. [30].

MgF(g) Ehlert et al. [38] reported the K's of the reactions,

A1F (g) + 2Mg(g) -AlF(g) + 2MgF(g) (1238°K to 1301°K), and 2MgF(g)-

Mg(g) + MgF

2

(c) (1205 °K to 1242 °K) . Third law values for AH0 are

47.5 kcal and -126.65 kcal, which lead to -54.1 and -53.3 kcal

for AHf°. An additional reaction, studied in Ehlert T s Dissertation,

9h
is 2NgF(g) -» Kg(g) -f MgF (g) for which the Dow Chemical Co. [30] reported Ah0 = -34.76 lccal. This results in AHf° = -51.5 kcal.

Gaydon [39] and Herzberg [40] report D°q = 3.2 ev and 4.2 ev,

respectively or AHf° = -21 and -41 kcal.

We have taken AHf° = -53.0 kcal.

The thermal functions were taken from the Dow Chemical Co. [30].

MgF^Cc) The thermal functions were taken from the Dow Chemical Co.

W].

Rudzitis et al. [42], from fluorine bomb calorimetry, reported

AHf° = -268.7 kcal. Gross et al. [43] reported AH° = -109.5 kcal

for Mg(c) + PbF^Cc) -» MgF^Cc) + Pb(c) which results in AHf° = -268.2

kcal. From Kapustinskii and Samplavskaya [44] we obtain AH = -94.8

kcal for Mg

2

Si0

4

(c) + 725.2(HF + 4.442 H O) - 2MgF

2

(c) + H

2

SiF

6

+ 4^0

+ 715.2 (13F + 4.510 l^O) and AHf ° = -266.3 kcal.

From Guntz 1 [45,46] reactions we obtain AH = 2.8 kcal for MgSO^

(440 H

2

0) + 2KF (220 H O) - MgF

2

(c) + K

2

S 0

4 (880 H O) and AH = -30.2

kcal for MgO + 2HF(110 H

2 0) -» MgF2

(c) + H

2

0. These result in AHf° = -266.7 and -257.5 kcal, respectively, von Wartenberg [47] reported

AH = -109.6 kcal for the solution of Mg in aqueous HF, from which we

calculate AHf° = -262.0 kcal. Petersen's [48] AH for MgCl

2

(440 H

2 0)

+ 2AgF(220 H

2

0) -* 2AgCl(c) + MgF

2

(c) results in AH = -28.1 kcal and

AHf° = -265.2 kcal. Torgeson and Sahama's [34] reaction of Mg(01I)

2

(c, 25°C) with HF(4.44 H

2

0) at 73.7°C results in AH = -30.9 kcal and

AHf 0 = -267.5 kcal. We have taken AHf ° = -268.5 kcal.

MgF

2 (g) The thermal functions used were obtained from the Dow Chemical Co. [30].

There have been many measurements of the vapor pressure over the

crystal and liquid. Table I summarizes the 2nd and 3rd law AH°subl

obtained. The "best" value is 95.5 kcal and AHf ° = -173.0 kcal.

95
Tabic I

AH° subl

Investigator Temperate re °K Method 2nd Lav 3rd Law

Berkowitz and Marquart [49] 1450 Torsion effusion 91.3 94.68

Green et al. [50] 1241-1492 Knud sen effusion 93*8 96.1

Hammer and Pask [51] 1451-1533 (c) ii ii 98.8 96.1

1568-1613 (liq) ti it 90.4 96.2

1413-1518 Torsion effusion 92.9 96.2

1539-1614 ii ti 96.4 96.2

Greenbaum et al* [52] 1273-1513 ti ii 84.0 91.5

Margrave [53] 1241-1492 Knud sen effusion 93.8 96.1

Le Boucher [54] 1934-2129 Manometric 99.9 96.0

Hildenbrand et al. [55] 1425-1533 (c) Torsion effusion 104.8 96.0

1540-1606 (liq) ii ii 102.8 95.9

Hildenbrand and Theard [56] 1326-1527 (c) it n 91.5 93.3

1544-1604 (liq) ii ii 82.4 95.1

Gunther [57] 1284-1530 Knudsen effusion 95.4 95*6

MgCl(g) Herzberg [40] and Gaydon [39] select D°q to be 3.2 ev and

2.7 ev, respectively. These result in AHf° = -10 and -Hi kcal.

The thermal functions were obtained from the Dow Chemical Co,. [41].

MgCl^Cc) The thermal functions were obtained from the Dow Chemical

Co. [58]

.

Bommer and Hohman [59] measured the AH at 293°K for Mg(c) and MgCl^Cc)

in 0.1N HC 1 to be -112.5 and -37.85 kcal, respectively. We obtain AH = -74.3 kcal for Mg(c) + 2HC1(0.1N) -» MgCl

2 (c) + H (g) and AHf ° - -153.9

keal. Similarly Shomate and Huffman [16] obtained, in solutions involving 77.2HC1 # 4190 ^0, AH = -111.285 and -36.560 kcal, respectively,

or AH = -74.725 kcal for Mg(c) -H 77.2(I1C1 + 54.275) -*MgCl (c) + 75.2

(HCl + 55.718 K

2 0) + H

2 (g) and A - -153.28 kcal.

Sano [60] measured the equilibrium MgCl

2 (c) + H^OCg) MgO(c) +

2HCl(g) in the range 796°K to 894°K. We obtain 2nd and 3rd law AH° = 19.7 and 23.14 keal/mol MgCl and AHf 0 = -149.9 and -153.28 kcal.

96
Treadwell [61,62] and Sane [63] measured the equilibrium for MgCl^Cc)

+ £C>2 -* MgO(c) -!~ Cl 9 (g) in the temperature ranges G20°K to 976°K and C65°K

to 943 °K, respectively. The 2nd and 3rd law 411° 1 s are 9.0 and 9.42 kcal,

from Treadwell's measurements, and 8.3 and 9.72 kcal from Sano's, which

lead to AHf° = -152.8 and -153.23, and -152.1 and -153.6 kcal, respectively. Similarly from the results of Tsuchiya [64] in the temperature

range 823°K to 973°K we obtain Z9If° = -151.6 and -153.6 kcal from the

2nd and 3rd law approaches. In the temperature range 1013°K to 1153°K

(MgCl^Cliq)) we obtain AH£° = -161.6 and -157.6 kcal, respectively.

Reznikov's [65] measurements at 1023°K to 1223°K lead to 2nd lav; and

3rd law AHf°'s = -160.3 and -152.1 kcal, respectively.

Egan et al. [66] from EMF measurements on the reaction Mg(c) +

2AgCl(NaCl) -* MgCl^Cc) + 2Ag(c) combined with other data on the

Ag/(AgCl - NaCl) half cell obtain the Z£f° of MgCl^Cc) at 673°, 723°

and 773°K. Their values lead to a 3rd law Ahf° = -154.14 kcal. From

the cell measurements of Treadwell et al. [67], Markov et al. [68],

Lorenz and Velde [69], and Talcahashi [70] on the reaction Mg(c,liq) +

Cl

2 (g) MgCl^Cliq) we obtain 3rd law AHF°'s = -159.9, -154.9, *-152.96,

and -153.18 kcal, respectively.

MgCl^Cg) The estimated thermal functions used in the calculations

were obtained from the Dow Chemical Co. [7].

Schrier and Clark [71] have shown that the gaseous species over

MgCl^Cliq), in the range 1200°K to 1400°K, is about 30% dimer. They

have also measured the total vapor pressure. Correcting for the

dimerization we obtain 2nd and 3rd law AH°subl =57.6 kcal and 58.0

kcal, respectively. Using their equilibrium constants for the dimerization process we have corrected the measurements of Kushkin et al.[72]

(1173°K to 1323°K) to 43.6 and 57.1 kcal, respectively, the measurements of Fischer et al. [73] (1136°K to 1435°K) to 58.0 and 56.9 kcal,

Maier [74] (1056°K to 1400°K) to 50.6 and 57.2 kcal.

Berkowitz and Marquart [49], from Knudsen effusion-mass spectroscopy

measurements, reported a monomer pressure at 921°K of 3.84 x 10 atm.

97
and ALIsubl - 54.6 kcal at SOO°K. These measurements result in a 3rd

law AK° - 56.4 kcal and a 2nd law ,:MI° - 55.4 kcal.

Hildenbrand et al. [55] reported vapor pressure results from torsion effusion measurements over the temperature range 800 °K to 985 °K.

Monomeric vapor was assumed. Second and third law AH°'s of 61.8 kcal

and 57.8 kcal are obtained. We have selected AH°subl = 57.6 kcal.

MgCl 9 (aq, std. state, m = 1) The final values were obtained from

the ions. See Mg (aq, std. state), MgCl^Caq), Mg (CIO^) (aq, std.

state, m = 1), and Mg (aq) •

MgCl^Caq) Lange and Streek [75], Zdanovskii and Deryabina [76],

Thomsen [36], and Fricke [77] measured AHdiln of aqueous MgCl^.

Mishchenko and Yakovlev [78] measured the AHsoln at varying concentrations.

Measurements of the AHsoln MgCl^ * rH^OCc) lead to the following

values for AHf (aq, nH^O), where n is the final concentration.

Corrections to 25 °C have been made. (See Table II.)

MgCl

2

*H

2 0(c) The Cp° and S° were obtained from Kelley and King [85],

From Shomate and Huffman's [16] measurements on the solution of

Mg(c) and MgC^'H^CKc) we obtain Ah = -84.15,7 kcal for Mg(c) + F^CKliq)

+ 7 7 . 2 ( HC 1 + 54.275H

2 0) - MfeCl^H 0(c) + 75.2(HC1 + 55.718H 0) + H (g),

and AHf ° = -231.02 kcal.

MgCl

2

• 2H

2

0 (c) The Cp° and S° were obtained from Kelley and King [85].

As for MgCl

2

(c) and MgCl

2

*lI2

0(c) we obtain, from the measurements

of Shomate and Huffman [16] AH = -90.675 kcal for Mg(c) + 97.2(HC1 +

54.275) + 2H

2

0(liq) - MgCl * 2H 0(c) + 75.2(HC1 + 55.718^0) + H

2 (g)

and AHf 0 = -305.86 kcal.

Auzhbikovich [86] reported AH0 = 16.4 keal/mol H

2

0 for the decomposition of the dihydrate to the anhydrous salt, or AHf° = -306.3 kcal.

98
Tabic ii.

System Investigator AHf

kcal /mol

nll

2

0 t °C of

Mens

.

MgCl

2

-6H

2

0 1 . Samoilov [79] -190.79 1110 25

2. Voskresenskaya and

Ponomareva [80] -190.52 333 25

3. Thomsen [36] -190.88 400 18

4. Richardson and

Wells [81] -188.30 22 22.8

5. Berthe lot and

Ilosvay [82] -190.49 200 12.7

6. Mishchenko and

Yakovlev [78] -190.79 1176 2

-189.95 52 2

-187.15 11.45 2

MgCl

2

-4H

2

0(c) 1 . Thomsen [36] -191.23 400 18

MgCl

2

-2H

2

0(c) 1 . Thomsen [36] -190.66 400 18

MgCl

2

(c) 1 . Mishchenko and

Yakovlev [78] -190.92 2270 2

2. Mishchenko et al. [83] -190.8 1110 25

3. Thomsen [36] -189.85 800 18

Mg(c) + equiv.

am't. HC1-200 H

2

0 1 . Richards et al. [84] -189.56 400 20

KgCl

2

*4H

2

0(c) The Cp° and S° were obtained from Kelley and King [85],

As for MgCl^*2H^0(c) , we obtain, from Shomate and Huffman's [16]

measurements AH = -102.056 kcal for Mg(c) 4- 77.2(HC1 + 54.275) +

4H

2

0(liq) - MgCl

2

*4H

2

0(c) + 75.2(HC1 + 55.718 HO) and AHf ° = -453.87

kcal.

Kondirev and Berezovskii [87]

,

Derby and Yngve [88], Sano [89], and

Auzhbikovich [86] measured the decomposition pressure of the hexahydrate

to the tetrahydrate. A log p vs 1/T plot of the data results in AHf° = -453.99 kcal.

99
Kondircv and Bo.ro:: ovskii [87] and Sano [90] measured the decomposition

pressures of the tetrahydrato to the dihydra tc. A log p vs 1/T plot results in AHf° = -454.05. Auzlibikovich ' s measurements result in AHf° - -457.1.

MgCl

2

*6H

2

0(c) The Cp° and S° were obtained from Kelley and King [85].

As for KgCl^^H^OCc) we obtain from Shomate and Huffman’s [16]

measurements AH = -108.836 kcal for Mg(c) + 77.2(HC1 + 54.275) + 6H^0

(liq) - MgCl

2

-6H

2

0(c) + 75.2 (HC1 + 55.718 1^0) and AHf° = -597.28 kcal.

Mg(C10^)

2

(c) Vorob'ev et al.. [91] reported AHsoln in 800 H

2

0 to be

-37.08 kcal. This results in AHf° = -135.97 kcal. Drakin and Chzhan

[92] reported four measurements in the range from m = .02 to .09 (where

m is the molality) , which lead to AHf° = -135.68 kcal. Smeets' [93]

measurements for m = 0.12 result in AHf° = -135.53 kcal. Measurements

have also been reported by Smith et al. [94]. We have selected the

first mentioned value.

Mg (CIO.) (aq, std. state, m = 1) The final values were obtained from

2+

the ions. See Mg (aq, std. state, m = 1), MgCl

2

(aq) and Mg (NO^) (aq)

.

Jongenburger and Wood [95] measured the AH diln from 3.2 to .0018

molal

.

Vorob'ev et al. [91] reported AH = -36.11 kcal for the reaction,

MgO(c) + 2HC10

4

*800 H O -» Mg(Cl(>4

) *800 H O + H O. This results in

AHf = -173.28 kcal for Mg(C10

4

) 2

*800 H O and AHf° = -173.63 kcal.

Mg (C10

4

) 2

’6H

2

0(c) Smeets [93] reported measurements of AHsoln at

18 °C for the hexahydrate and the anhydrous salt. We obtain AH° = -38.71 kcal for Mg(C10

4

) 2

(c) + 6H^0(liq) - Mg (CIO^ • 6H

2

0(c) and AHf° = -584.57 kcal. Similarly from Smith et al. [94] we obtain AH° = -32.7

kcal and AHf° = -578.6 kcal. Their value for AH soln = 0.8 kcal for

the hexahydrate leads to AHf° = -583.8 kcal. Nosova [96] reported

AH soln to a final concentration of 0.07 m = 1.45 kcal, from which

we obtain 4Hf° = -584.39 kcal.

100
Linke [5] Lists the saturation concentration to be 4.48 molal.

Using this and the activity coefficient and osmotic coefficient from

Robinson and Stokes [6] we obtain A£°soln - -7.60 kcal, which results in AGf° = -445.34 kcal and S° = 124.5 e.u.

MfiOKCl (c) Kelley [97] evaluated the data on the MgOIiCl(c) system

and obtained for HgCl^ • H^OCc) MgOHCl(c) *f IlCl(g) 411° = 17.82 and

AG° = 8.34 kcal. These lead to AHf° = -191.1 kcal, AGf° = -174.9,,

and S° = 20.0 e.u.

Savinlcova and Dagtyareva [98] reported the equilibrium from 743°K

to 1023°I< for MgCl^ (solid soln) I-I 0(g) — MgOIICl (solid soln) + KCl(g).

The K’s include the activities. Their results give ALI° = -1.5 kcal

and AHf° = -191.1 kcal. Vel'nyanskii and Savinkova [99] do not give

the activities; hence, their values have not been used.

MgBr^Cc) Beketov [100] reported AHsoln in 800 11^0 = -43.30 kcal,

from which we obtain AHf° = -125.26 kcal. Finch et al. [101] report

AH = -35.23 kcal for the reaction of MgO(c) in excess HBr(m = 0.5)

to form MgBr^^OOO H^O, and AH = -43.14 kcal for the solution of

MgBr^Cc) in excess HBr(m = 0.5) to form MgBr^^OOO II^O. Correcting

for the concentration change, we obtain AH - 7.78 kcal for MgO(c) +

2HBr(aq) -* MgBr^Cc) + H O(liq), and AHf° = -125.36 kcal.

Toguri et al. [102] reported ^g °]_ 073 °k~

0.267 kcal for -^MgBr^ (liq)

+ HCl(g) -» -g-xigCl^ (liq) + HBr(g). Using estimated thermal functions

from the Dow Chemical Co. [58] we obtain AH° = -2.3 kcal and AHf° = -121.9 kcal.

S° has been estimated as 28.0 e.u. by Kelley and King [85].

MgBr^Cg) Berkowitz and Marquart [49] obtained the vapor pressure by

the mass spec troscopy-Knud sen effusion method. A 3rd law AH° from

measurements at 798°K and 84-2°K is 49.7 kcal. The 2nd law value, at

727°K, results in AH° = 52.2 kcal. We have taken AH°subl = 51.3 kcal

and AHf 0 = -74.0 kcal.

101
MgBr9 (aq, std. stale, m 1) The values were obtained from the ions.

KgBr

9 (aq) Lange and Strode [75] measured the heats of dilution.

MgBr9

• 6 ^

0 ( 0 ) The saturation solubility was obtained from Linke [5];

the activity and osmotic coefficients at saturation from Robinson and

Stokes [ 6 ]. The resultant AG°soln = -7.13 keal. We have estimated

S° = 95. e.u. This results in AHf° - -575.9 keal. A value of 40.7 kcal

is obtained for the AH° for the reaction MgBr^* 6 ^

0 ( 0 )

-* MgBr^Cc) +

6 H O(liq). This appears high in relation to AH° = 34.1 for the comparable chloride system; however, from the differential AH soln (obtained from the solubility measurements), which was corrected to infinite dilution we obtain AH°soln = -3.4 kcal and AHf° = -576.2 keal.

Mgl^Cc) From Beketov's [100] measured AH soln in 880 11^0, we have

AHf° = -87.1 kcal. Finch et al. [101] report AH = -35.10 kcal for the

reaction of MgO(c) in excess HI (m = 0.5) to form Mgl^*2000 H^O; and

AH = -49.75 kcdL for the solution of MgBr^Cc) in HI to form

MgBr2*9000 H^O. Correcting for the concentration change, we obtain

4H =14.50 kcal for MgO(c) + 2HI(aq) -* MgBr^Cc) + H^OCliq) and AHf° = -87.0 kcal.

Kelley and King [85] have estimated S° = 31.0 e.u.

Mgl^Cg) Berkowitz and Marquart [49] measured the vapor pressure by

the mass spectroscopy-Knudsen effusion method. A 3rd law AH° from

measurements at 757 °K and 734°K is 45. kcal (the A(G°-H° )/T was estil y o mated). The 2nd law value at 640°K results in 46.4 kcal. We have

taken AH°subl = 46 kcal from which we obtain AHf° = -41 kcal.

Mg^teq, std. state, m = 1) The values were obtained from the ions.

102
Mgl 9 (aq) The values were estimated from a consideration of the AHdiln

of MgCl 9 and NgEr9 , and the Cl-Br-I system of the monovalent electrolytes .

llgSO^(c) The Gp° and S° were obtained from Kelley and King [85].

The following values for AHsoln have been obtained: Thomsen [36]

-20.7 kcal (nH

2

0 = 420); Berthelot and Ilosvay [82] -20.8 (nll^O = 100);

Pickering [103] -20.9 and [104] -20.8 kcal (nH

9 0 = 420). These result

in AHf° - -307.1, -306.8, -307.0, and -307.1 kcal, respectively.

Kelley [105] evaluated the data on the equilibrium 2KgS0^ -* 2MgO(c)

+ 2S0

2 (g) + 0^(g) and obtained AK° = 196.0 kcal, which leads to AHf° = -312.8 kcal. The results of Dewing and Richardson [106] yield All

0 = 189.6 kcal and AHf 0 = -309.6 kcal.

From Knopf and Staude's [ 107 ] equilibrium measurements for MgSO^(c)

-» MgO(c) + SO^(g) we obtain AH° =58.3 kcal and AHf° = -296.7 kcal.

I Q

MgS0,(aq, std. state, m = 1, undissociated) Sillen and Martell [28] ~ 2+ 2 - list the K's and AH° for Mg + SO^ -* MgS0^(aq, undissoc). Using the

measurements of Hair and Nancollas [108], AH° =4.84 kcal and log K =

2 . 25 , we obtain AHf° = -324.1 kcal and AGf° = -289.74 kcal.

MgSO. (aq, std. state, m = 1) The final values were obtained from the

24- ions. See Mg (aq, std. state, m = 1).

MgSO^ (aq) The heats of dilution were measured by Lange [109], Lange

and Streeck [110], Lange and Messner [111,112], Plake [113], and

Thomsen [36]. Kaganovich and Mishchenko [114] measured AHsoln of

MgSO^* 711^ 0 ( 0 ) as a function of the concentration. From Thomsen's [36]

reported values for the reactions: (1) MgCl

2

(200 H^O) 4- l^SO^^OO H^O)

-> MgS0

4

(200 H

2 0) 4- 2HC1 (100 H^O) ; (2) MgCl

2

(800 H

2 0) 4- H

2

S0

4 (400 ^0) -

MgS0

4

(400 H

2

0) 4- 2HC1 (400 HO); and (3) MgS0

4

(400 H O) 4- 2HN0

3 (400 ^0)

-» Mg(N0

3

) 2

(800 H

2

0) 4- H

2

S0

4 (400 HO), we obtain (1) AH = -3.82 kcal,

(2) AH = -3.76 kcal, and (3) AH = +3.99 kcal, which result in (1) AHf

(200 H

2 0) = -327.70, (2) AHf (400 ^0) = -327.92 and (3) AHf (400 ^0) =

103
-328.12 kcal. These arc in good agreement with the values obtained from

the use of the heats of diln and the ions.

MgSO^*H0 0(c) The Cp° and S° were obtained from Kelley and King [85].

Thomsen [36] and Pickering [103] measured AH soln in 400 I^O. Their

results lead to AHf° = -382.5 and -384.0 kcal. Jamieson and Frost [115]

reported AH (soln, os) = -14.26 kcal which results in AHf° = -382.9 kcal.

Kohler and Zaske [116] reported AH = 15.0 kcal for the decomposition

to the anhydrous sulfate and H^OCg). This results in AHf° = -379.9 kcal.

MgSO^-H^OCamorph) Jamieson and Frost [115] reported AH (soln, co) = -20.8 kcal; AHf°, then, is -376.4 kcal

Frost et al. [117] report S° = 33.0 e.u.

MgSO^^H^OCc) Thomsen's [36] AH soln in 400 H^O is -11.4 kcal, or AHf ° = -453.2 kcal.

Kohler and Zaske [116] reported AH = 25.3 kcal for the decomposition

to the anhydrous salt and ^0^) ; this results in AHf° = -455.8 kcal.

MgSO^^H^OCc) Thomsen's [36] AH soln in 400 H^O is -4.45 kcal or

AHf ° = -596.7 kcal.

Kohler and Zaske [116] reported AH = 25.8 kcal for the decomposition

of the hexahydrate to the tetrahydrate and Il^OCg). AHf 0

, then, = -597.4

kcal.

MgSO^* 6 ^

0 ( 0 ) The Cp° and S° were taken from Kelley and King [85].

Thomsen [36] reported AH soln in 400 H^O to be +0.02 kcal from which

we obtain AHf° = -737.8 kcal.

Carpenter and Jette [118], Rolla and Accame [119], Bell [120], and

Kohler and Zaske [116], reported values for AH for decomposition of the

heptahydrate to the hexahydrate and H^OCg). Their values are 14.0,

14.6,14.1, and 14.7 kcal, or AHf ° = -738.1, -737.5, -738.0, and -737.5

kcal, respectively.

lQli
NgS0^*7H9 0(c) Kaganovich and Mishchenko [114] measured AHsoln from

m = .25 to m - 2,2. Their values at these concentrations are 3.12 and

4.54 lccai. The 21 measurements result in AHf° = -809.92 kcal. Kapustin1 skii and Samoilov [121] reported AHsoln = 1.82 kcal at m = .03. This

results in AHf ° = -808.20 kcal. From Perreu's [122] AHsoln measurements at 284°K, from nl^O = 75 to nll^O = 21, we obtain AH = 4.0 to

4.5 kcal or AHf ° = -809.74 to -809.88 kcal. From Thomsen's [36] and

Pickering's [103] AHsoln, 400 H^O we have AH = 3.74 and 3.90 kcal or AHf° = -809.8 and -810.00 kcal.

From the solubility given by Linke[5] and the activities and osmotic

coefficients given by Robinson and Stokes [6] we obtain AG°soln =2.29

kcal and AGf° = -685.8 kcal. Using this value for AGf° and a AHf° = -809.92 we obtain S° = 87 e.u. which appears low. From the decomposition pressure measurements of the heptahydrate to the hexahydrate of

Bell [120] we obtain AH° = 14.1 and AG° = 2.42 kcal from which we obtain

S° = 89.0 e.u. Kohler and Zaske's [116] decomposition pressure is in

agreement.

MgsN (c, a) Mitchell [123] reported the values of AH for the following reactions to be -287.89 kcal and -32.08 kcal, respectively.

(1) Mg

3

N

2

(c) + 231. 6HC1* 12570 HO 224. 6HC1* 3MgCl 0

• ZNH^Cl- 12570 H^O

(2) 2NH

3

(liq) + 226. 6KC1- 12570 H O - 224. 6HCl-3MgCl

2

* 2NH Cl* 12570 1^0

Using the AH of Shomate and Huffman [16] for. the reaction of Mg(c) in

HCl(aq) and the AHvap of NH

3

(liq), he obtains AH° = -88.05 kcal for

3Mg + 2NH

3 (g) -* Mg3

N

? (c) + 3H

2 (g) from which we obtain AHf ° = -110.09

kcal.

Neumann et al. [124] reported the values of AH for the following

to be -284.8 and -336.0 kcal, respectively.

(1) Mg

3

N

2 + 8 (KC1 + 20 H

2 0) - (3MgCl

2

+ 2NH

4

C1) (aq)

(2) 3Mg (c) + 6 (HG1 + 20 ^0) - 3MgCl

2

(aq) -1- 3H

2 (g)

Using the AH = 4.14 kcal from Juza et al. [125] for the solution of

NH^ClCc) in HCl(aq) they obtain AH = -42.9 kcal for 3Mg(c) + 2NH

4

C1 (c) - Mg

3

N

2

(c) + 2 (HC1 + 20 H

2

0) + 3H

2 (g) from which AHf ° = -114.9 kcal.

105
Neumann ct al. [126] directly determined the value of AHf° to be

-116.6 keal.

The results of Brunner are cited by Neumann et al. [124], AH = -177.0 kcal for MggN C c ) H-5 0 (° )—» 3Mg (Oil)

2

(ppt . ) + 2NH^(aq) from -which

we obtain AHf° = -111.4 kcal. Matignon [127] and Moser and Herzner

[128] measured the AH = -279.7 and -269.9 kcal, respectively for the

reaction of Mg^N^ with H^SO^^OO H^O. The values for AHf° are -133.0

and -143.0 kcal.

Dreger [129] measured the decomposition pressure to Mg(g) and N^(g)

from 1118° to 1254°K, and obtained a AH° apparent = 295.0 kcal, or a AHf° = -189.1 kcal. Blank [130] obtained nonequilibrium values from

Torsion effusion measurements in the range 1000-1250 °K of 286.3 and

218.7 keal/mol Mg^l^ for the 3rd law and 2nd law values, respective iy.

Ilildenbrand and Theard [56], in similar measurements, obtained a 2nd

law non equilibrium AH° = 309 kcal. These values lead to AHf° = -180.4,

-112.8, and -203.1 kcal. Both Blank and Hildenbrand determined the

condensation coefficients and corrected their vapor pressures to obtain equilibrium values. Blank's results now yield AH° = 242.3 kcal

(3rd law) and 239.1 kcal (2nd law) and AHf°= -136.4 and -133.2 kcal,

respectively. Hildenbrand ' s measurements result in an equilibrium

AH° = 243.5 kcal and a AHf° = -137.6 kcal. The latter three values

are in good agreement; however, as Hildenbrand points out, there is a possibility that there is a secondary reaction going on that would

interfere with the decomposition reaction. Until there is further

evidence supporting this, we have selected the first mentioned AHf° = -110.1 kcal.

The Dow Chemical Co. [131] tabulates the thermal functions.

Mg(N0

3

) 2

(c) The Cp° and S° were obtained from Kelley and King [85].

Young [132] measured the AH's of the following reactions:

(1) 2HN0

3

*26.5 H

2

0 + MgCl

2

*75.2HCl -4190 ^0 -» Mg(N0

3

) -77.2HC1-4216.5 ^0; AH = 0.198 kcal

(2) Mg(N0

3

) 2

• 77.2HC1-4190 HO + 26.5 H^O(liq) -

Mg(N0

3

) 2

*77.2HCl*4216.5 1^0; AH = -.113 kcal

106
(3) Mg(N0

3

) (c) + 77.2HC1-4190 I-IO -

Mg(N0

3

) 2

-77.2HCl*4190 1^0; AH- = -20.634 kcal

Using the reaction of Shomate and Huffman [16] , Mg (c)+77. 21101*4190 - MgCl *75.2 HC1-4190 H

2

0+H

2 (g) ;AH = -111.285 kcal, we obtain AH = -90.340 kcal for Mg(c) + 2HN0

3

*26.5 H

2

0 - Mg(N0 ) (c) + H (g) and Arif ° = -188.97 kcal.

Mg(N0 ) (aq, std. state, m = 1) The final values were obtained from the

24- ions. See Mg (aq, std. state, m = 1)

Mg(N0^)

2

(aq) Lange and Streeck [110], Hammerschmid and Lange [133],

Ewing et al. [134], and Thomsen [36] measured AH diln.

Pickering [135], Thomsen [36], and Ewing et al. [134] measured AH

soln. of the hexahydrate. Their results lead to AHf = -210.25 kcal

(400 H

2 0), -210.58 kcal (400 H

2 0), and -210.04 kcal (130 HO), respectively. Ewing also measured the AH soln. of the anhydrous salt, from

which we obtain AHf (130 ^0) = -210.20 kcal.

Mg (N0

3

) 2

* 2H

2

0 (c) Ewing et al. [134] measured the AH soln. of the anhydrous salt and that of the dihydrate. We obtain AH = -11.18 kcal for

Mg(N0

3

) 2

(c) + 2H

2

0(liq) - Mg(N0

3

) 2

-2H

2

0(c) and AHf ° = -336.8 kcal.

Mg(N0

3

) 2

*6H

2

0(c) Young [132] measured the AH soln. of the hexahydrate

and anhydrous salt in aqueous HC1 (See Mg (N0

3

) 2

(c) ) . The results lead

to AH° = -25.729 kcal for Mg(N0

3

) 2

(c) + 6H0(liq) -> Mg (NO^ *6^ 0(c)

or AHf° = -624.59 kcal. Similarly, from Ewing et ai.'s [134] AH soln.

in H

2

0 we obtain AH = -25.88 kcal or AHf° = -624.74 kcal.

Lloyd et al. [136] reported decomposition pressure measurements to

the anhydrous salt in the temperature range from 293°K to 333 °K. We

obtain AHf° = -618.3 kcal.

From the solubility given by Linke [5] and the activity coefficients

and osmotic coefficients given by Robinson and Stokes [6] we obtain

AG°soln = -4.11 kcal or AGf° = -497.93 kcal. This results in ASf° =

107
-425 .3 e.u. ana £> — 109 .

j

e.u. Hiis appears a little high. We have

estimateo S = 100 e.u. and nave adjusted ACf° accordingly.

Mgc

0 (c) Irmann [137] reported All = -78 kcal for the reaction MgC^Cc) +

180 HC 1 (m = 2.53, ^

aCl

= 3.16) - MgCl

2

(aq) + 178 1IC1( m = 2.50, m^

3.16) + C

2

H

2 (g). This results in AHf° = 20 kcal.

^g 9 C

3

(c) Irmann [ 137) reported AH = -198 kcal for the reaction

>Is 2

C3^ + 3601101 = 2.53, m

NaC1

= 3.16) - 2MgCl

2 (aq) + 356IIC1 (m = 2.51, m

NaCl

= 3 * 16 ^ + C

3

H

4

^S)« Using AHf° (g) = 44.3 kcal, we

obtain AHf° = 17 kcal.

MgCO^Cc) The Cp° and S° were obtained from Kelley and King [85];

the high temperature functions from Kelley [138],

Kapustinskii and Stakhanova [139] measured the following AH's:

(1) MgC0

3

(c) .+ 2KC1 (aq) -» MgCl^aq) + H

2

0(liq) + C0

2 (g); AH = -12.80

kcal

(2) MgO(c) + 2HC1 (aq) -» MgCl

2

(aq) + H O(liq) ; AH = -36.32 kcal

This results in AH = +23.52 kcal for KgCO^Cc) -* C0

2 (g) + MgO(c), or AHf ° = -261.4 kcal.

Roth [140] reported the AH° decomp. = +23.6 kcal or AHf° = -261.5

kcal. Berthelot [141] reported AH = 2.7 kcal for the precipitation

of MgC0

3

from ^00^220 H O) and MgS0

4 (220 ^0). We obtain AHf° = -268.1 kcal. Ellis and Mortland [142] and Foldvari-Vogl and Kliburszky [143] obtained AH°decomp. from differential thermal analysis

methods, to be 27.6 kcal and 27.0 kcal, respectively, or AHf° = -265.5

and -264.9 kcal.

We obtain from Marc and Simek's [144] vapor pressure measurements

AH°decomp. = 28.2 kcal (3rd law) and 26.4 kcal (2nd law) or AHf° = -266.1 kcal and -264.3 kcal.

Langmuir [145] reviews the above data as well as the solubility

measurements and the derived AGf° values and points out the inconsistencies in the stability relationships in the Mg0-C0

2

-H

2

0 system.

We have accepted his interpretation and calculations to obtain AG° = 0.665 kcal for MgC0o

• 3K

2

0(c) -> MgC0

3

(c) + 3H

2 0(liq). Using our value

for AGf° for the trihydrate = -412.6 kcal, we obtain A£f° = -241.9 kcal.

108
Mg 0 Si(c) Kubaschewski and Villa [146] reported AHf 0 = -18.6 kcal.

Eremenko and Lukashenko [147], from EM? measurements obtained E(in ev)

0.2075 - 0.77x10 ^T for the range 673°K to 873°K, from which we obtain AHf°^

2

<> K

= -19.1 kcal. This corrects to AHf ° = -18.7 kcal.

Grjotheim et al. [148] measured the decomposition pressure in the range

1130 to 1273 °K by the transpiration technique. We obtain AH° =41.1

kcal /mol Mg(g) or AHf 0 = -11.6 kcal.

From Eremenko and Lukashenko we also obtain a ASf°(773°K) = -7.1

e.u. which, assuming a 4Cp = -1 cal/mol deg, corrects to ASf° = -6.1

and S° = 14.0 e.u. This value appears low. Mannchcn and Jacobi [149]

reported Cp measurements from 12°I< to 300°K on Mg Si(c) and S° = 19.8 cal/mol. Assuming their reported S° is for Mg^ we °b~

tain S° Mg^SiCc) = 18.6 e.u. and a ASf° = -1.5 e.u. For the corresponding Ge compound (S°£^(c) = 7.43 e.u.) we have

S° = 20.7 e.u. and 45

f

0 = -2.35 e.u. In comparison with these figures

we feel 18.6 e.u. is high (and -1.5 e.u. too positive). We have

therefore adjusted S° to = 18.0 e.u.

MgSiO^(c) Furukawa and Reilly [150] evaluated the low temperature

Cp and high temperature heat content and have tabulated the thermal

functions up to 2000°K.

Torgeson and Sahama [34] by HF soln. calorimetry of MgCOH^Cc),

SiO^Cc, quartz), and MgSiO^(c) obtained AH = 0.16 kcal for Mg (OH)

2 (c)

+ SiO^c) -» MgSiO (c) + ^OCliq). This results in AHf° = -370.22 kcal.

Henderson and Taylor [151] reported ^°]_323 °k = -5.1 kcal for the

formation from the oxides. This results in AHf° = -368.5 kcal.

Mg

2 SiO^(c) Furukawa and Reilly [150] tabulated the thermal functions

up to 2000°K.

Torgeson and Sahama [34] by HF soln. calorimetry of Mg (OH)

2 (c),

Si02(c, quartz), and Mg SiO (c) obtained AH = 2.58 kcal for 2Mg(OH)2(c)

+ Si02(c) — Mg

2

SiO^(c) + 2H O(liq), from which we obtain AHf 0 = -520.45

kcal.

109
King et al. [152] from HF soln. calorimetry obtained AH° = -13.86

kcal for 2MgO(c) + SiO^Cc) -* Mg^SiO^ (c) which

kcal. Henderson and Taylor [151] reported A3

Mg^SiO^ (c) which leads to AHf° = -519.20

°1823°K

= kcal for

the formation of Hg^SiO^Cc) from the oxides. This results in AHf° = -515.4 kcal.

Mg^Si^O^ (OH)^ (c) King et al. [152] from HF soln. calorimetry obtained

AH° = -39.86 kcal for 3MgO(c) + 2Si0

2

(c) + 2H

2 0(liq) -* Mg Si 0

5

(0LI)

4

(c)

from which we obtain AHf° = -1043.4 kcal.

The Cp° and S° were also obtained from King et al.

Mg^Si^O^COlO^ (c) Barany [153] from HF soln. calorimetry obtained AH° = -44.9 kcal for 3MgO(c) + 4Si0

2

(c) + l^OQiq) -* Mg^Si^O^^COlO^ (c) from

which we obtain AHf° = -1415.5 kcal.

The Cp° and S° were obtained from Robie and Stout [154].

MgB 19 (c) The thermal functions were obtained from Germaidze et al.

. „5

[155] who also measured the Mg(g) pressure over the MgB^ to be 10

atm. at 1700°K. This results in AHf° = -53.4 kcal.

MgA^O^Cc) The Dow Chemical Co. [156] tabulated the thermal functions.

Navrotsky and Kleppa [157] measured the AH soln. of MgO(c), A^O^

(c, and MgAl^O^Cc) in 9PbO* SCdO’Al^O^ (melt) and obtained ^970 °K~

-8.72 kcal for the formation from the component oxides. This results

in AH° = -8.6 kcal and AHf 0 = -552.9 kcal.

Altman [20] from Knudsen effusion decomposition pressure measurements [MgAl^O^ (c) Mg(g) + |-02 (g) 4- A1

2

0

3

(c)], supports a AH° = -5

kcal for the formation from the oxides. Altman [158] from transpiration

experiments on the Al-MgO and Al-MgAl^O^ systems obtained AH° = -7 kcal.

Grjotheim et al. [159], by the transpiration me thod, measured the K's

for 4MgO(c) + 2Al(liq) “* MgAl^O^Cc) + 3Mg(g). They considered the system ideal. On this basis we obtain AH° = 7.3 kcal (2nd law) and -7.6

kcal (3rd law). Altman [20] corrects their results for the activity

110
of Al. Using the thermal functions mentioned above we obtain a 3rd

law m° = -8.2 kcal and = -552.5 keal. Grjotlieim et al. [160]

repeat their measurements and obtain a /ill 0 =4*1.1 kcal. In a later

series of measurements on the AI-Mg-SiO system they [161] obtain the

activity of Al and pressure of Mg(g) for the equilibrium process,

4MgO(c) 4- 2AlSi(liq) “^MgAl^O^Cc) 4-3Mg (g) . This results in Ah° = -7.4

kcal for formation from the oxides and tMIf° - -551.7 kcal. In a reaction involving MgO(c) and Al^C^(c) they [162] obtain AM0 = -11.1

kcal and AHf° = -555.4 kcal. Rao and Dadapc [163] measured the IC's

of the reaction, 4MgO(c) 4* 3AlCl(g) ^ MgA^O^c) 4- AlCl^(g) 4- 3Mg(g)

in the range 1298 °K to 1465 °IC. We obtain Z5if ° = -554.0 kcal (3rd law)

and a AH° = -9.7 kcal for formation from the oxides and AKf° = -554.7

kcal (2nd law) and a <5K° = -10.4 kcal.

Zaionchovskii and Rubai' skaya [164] reported 4Hf° = -567.1 kcal.

The first mentioned ALif° was selected.

Mg 0 Al. Si 0 (c) The Cp° and S° were obtained from Weller and King

2 4 5 1 o [165]; the high temperature heat content from Pankratz and Kelley [166].

Henderson and Taylor [151] reported ^°]_733 °k

= -12.5 kcal for

2MgO(c) 4- 2A1 0 (c) 4* 5SiO (c) -> Mg Al, Si 0 (c) from which we ob2 5 2 2 4-3 io

tain AHf ° = - 2177. kcal.

Ill
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119
Tabic III

Selected Values for Some Mg Compounds at 298 °K

Compound State AHf°

kcal/mole

AGf ° kcal/mol

Mg c 0 0

Mg g 35.30 27.04

Mg+ g 213.100

Mg2+

g 561.299

Mg2+ aq

std. state, m = 1 -111.58 -108.7

MgO macro crystal

(periclase) -143.81 -136.10

MgO micro crystal -142.92 -135.27

MgO g 4.

' MgH2 c -18.0 -8.6

MgOH+ aq

std. state, m = 1 -149.8

Mg (OH) 2 c -220.97 -199.23

Mg(0H) 2 ppt -220.0

Mg(OH) 2 aq

std. state, m = 1 -221.52 -183.9

Mg (OH)

2 g -13U

MgF g -53.0 -59.2

MgF 2 c -268.5 -255.8

MgF 2 g -173.0 -174.6

MgCl g o •

*

—

i i -16.

MgCl 2 c -153.28 -141.45

MgCl 2 g -95.7

MgCl2 aq

std. state, m = 1 -191.48 -171.4

50 H2 0 -190.23

100 h2 o -190 .59

400 H20 -190,. 94

1,000 H2 0 -191.080

5,000 H2 0 -191.269

10,000 H2 0 -191.323

8 wCM o -191.48

S°

cal/deg mol

7.81

35.502

-33.0

6.44

6.67

7.43

15.10

-35.6

52.79

13.68

61.73

55.8

21.42

- 6.0

120
Compound b lCIlC AlI£°

kcal/mole

Z£f 0 kcal/mole

S°

cal/deg

HgCl 2 ‘H2 0 c -231.03 -205.98 32.8

>AgCl 2

* 2H2 0 c -305.86 -267.24 43.0

MgCl2 *4H2 0 c -453.87 -388.03 63.1

MgCl 2 *6H2 0 c -597.28 -505.49 87.5

Mg(C104) 2

c -135.97

Mg(C104 ) 2 aq

std. state, m = 1 -173.40 -112.8 54.0

Mg(C104) 2 *6H2 0 c -584.5 -445.3 124.5

MgOHCl c -191.1 -174.9 20.0

MgBr2 c -125.3 -120.4 28.0

MgBr2 g -74.0

MgBr2 aq

std, state, m = 1 -169.68 -158.4 6.4

100 H2 0 -168.98

400 H2 0 -169.18

1,000 i-i 2 o -169.304

5,000 H2 O -169.476

10,000 H2 0 -169.528

00 H20 -169.68

MgBr2 *6H2 0 c -576.0 -491.4 95

Mgl2 c

1 00 ^1 . 0 -85.6 31.0

Mgl2 g -41

Hgl2 aq

std, state, m = 1 -137.96 -133.4 20.2

400 H2 0 -137.49

1,000 H2 0 -137.59

00 h2 o -137.96

MgS04

c -307.1 -279.8 21.9

MgS04 aq., std. state

m = 1, undissoc -324.1 -289.74 -1.7

121
Compound State zqif°

lccal/mole

4Gf°

kcal/mole

S°

cal/deg

WgS04

aq

std. state, m = 1 -328.90 -286.7 -28.2

50 H2 0 -327.41

100 h2 o -327.59

400 H2 0 -327.88

1,000 h2 o -328.08

5,000 H2 0 -328.358

10,000 h2 o -328.467

CO H2 0 -328.90

MgS04 *H2 0 c -382.9 -341.5 30.2

MgS04 *H2 0 amorph -376.4 -335,8 33.0

MgS04 .2H2 0 c -453.2

MgS04 -4H2 0 c -596.7

MgS04 *6H2 0 c -737.8 -629.1 83.2

MgS04 *7H2 0 c -809.92 -686.4 00 VO . Mg3N2 c -110.1

Mg(N03 ) 2c -188.97 -140.9 39.2

Hg(N03) 2 aq

std. state, m = 1 -210.70 -161.9 37.0

50 H20 -210.14

100 h2 o -210.16

400 H2 0 -210.28 . 1,000 h2 o -210.364

5,000 H2 0 -210.502

10,000 h2 o -210.551

CO H2 0 -210.70

Mg(N03

))2 *6H20 c -624.59 -497.3 108

MgC2 c 20

Mg2C3 c 17

MgC03 c, magnesite -261.9 -241.9 15.7

122
Compound State 4Gf°

lccal/mole

/.MIf ° kcal/molc

S°

cal/dcg mol

Mg2 Si c -18.6 i i— 1

00 . o 18.

KgSi03 clinoanstatite -370.22 -349.46 16.19

Kg2 Si04 c, forsterite -519.6 -491.2 22.74

Mg3Si2 05 (OH) 4

c j chrysotile -1043.4 -965.1 52.9

MS3 Si4°10( OH)2 Cy talc -1415.5 -1324.8 62.3

MgB 12 c -53. -52. 21.4

MgO*Al203 c -552.9 -523.1 19.27

Mg2Al4Si5 018 c f cordierite -2177 -2055 97.3

123
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THERMODYNAMIC PROPERTIES OF SELECTED LIGHT-ELEMENT AND SOME RELATED COMPOUNDS

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3 abstract This report presents the results and interpretation of five recent NBS

experimental studies of thermodynamic properties, two reviews which refine data

treatment and evaluation, and one new critical assessment of published heats of

formation. The heat capacity of beryllium nitride, Be3N2 , was precisely measured

from 0 to 315 K; after judicious correction for the irreducible impurities, the data

led to the common thermodynamic properties from 0 to 315 K, complementing earlier

NBS measurements from 273 to 1173 K. Precise high- temperature calorimetry gave the

heat capacity of tungsten from 1100 to 2600 K (showing no detectable difference

between two samples, one triple-zone-refined and 99.999% pure); finally corrected

results are given also for solid and liquid beryllium aluminate, B3A/ 2^4 » f rom

1200 to 2400 K. A mass-spec trometric investigation of aJL 2^3 containing 5.8% BeO

identified the high- temperature gas species and gave values for their standard heats

of formation. As part of the current NBS microwave and infrared infrared invest igaticjn

of the alkali-hydroxide molecules, the high- temperature microwave spectra of four

isotopic varieties of RbOH were observed and analyzed to give their molecular constant^

like CsOH (studied earlier), RbOH is linear, with a low-frequency bending vibration

of large amplitude. Two reviews deal with reaction calorimetry involving fluorine

compounds: One documents the inadequacy of estimation rules for unmeasured inorganic

fluorides and recommends a systematic cataloging of results to achieve better

consistency; while the other describes a new computer subroutine for the automatic

reduction of bomb-calorimetry data on organic fluorine compounds. As the result of an up-to-date critical evaluation of the published data giving AHf393 , A Gf395 > and

S§ 98 '°f magnesium compounds, values are documented and tabulated for 60 species of

InterestinRlighjt^eLement^cyjjiLicciti^

DD FORM1 NO V 65 1473 UNCLASSIFIED

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1 4 . K EY WORDSLINK A LINK B LINK C ROUE W T ROLE W T ROLE W T Thermochemistry

Fluorine Compounds

| Thermodynamic Properties

j Heats of Formation

Beryllium Nitride

Beryllium Aluminate

:! Microwave Spectra

RbOH

RboD

Magnesium Compounds

Tunsten, Enthalpy of Calorimetry

Rocket Propulsion

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It will also cover some of the work in acoustics,

applied mechanics, building research, and cryogenic

engineering. Issued quarterly. Annual subscription:

Domestic, $2.75; foreign, $3.50*.

TECHNICAL NEWS BULLETIN

The best single source of information concerning

the Bureau’s research, developmental, cooperative

and publication activities, this monthly publication

is designed for the industry-oriented individual whose

daily work involves intimate contact with science

and technology

for engineers, chemists, physicists,

research managers, product-development managers, and

company executives. Annual subscription: Domestic,

$1.50; foreign, $2.25*.

‘Difference in price is due to extra cost of foreign mailing.

NONPERIODICALS

Applied Mathematics Series. Mathematical

tables, manuals, and studies.

Building Science Series. Research results, test methods, and performance criteria of building materials, components, systems, and structures. Handbooks. Recommended codes of engineering

and industrial practice (including safety codes) developed in cooperation with interested industries,

professional organizations, and regulatory bodies.

Special Publications. Proceedings of NBS conferences, bibliographies, annual reports, wall charts,

pamphlets, etc. Monographs. Major contributions to the technical literature on various subjects related to the

Bureau’s scientific and technical activities. National Standard Reference Data Series.

NSRDS provides quantitative data on the physical

and chemical properties of materials, compiled from

the world’s literature and critically evaluated.

Product Standards. Provide requirements for

sizes, types, quality and methods for testing various

industrial products. These standards are developed

cooperatively with interested Government and in- dustry groups and provide the basis for common

understanding of product characteristics for both

buyers and sellers. Their use is voluntary.

Technical Notes. This series consists of communications and reports (covering both other agency

and NBS-sponsored work) of limited or transitory

interest.

CLEARINGHOUSE

The Clearinghouse for Federal Scientific and

Technical Information, operated by NBS, supplies

unclassified information related to Governmentgenerated science and technology in defense, space,

atomic energy, and other national programs. For

further information on Clearinghouse services, write:

Clearinghouse

U.S. Department of Commerce

Springfield, Virginia 22151

Order NBS publications from:

Superintendent of Documents

Government Printing Office

Washington, D.C. 20402