bluuebunny/crossref_metadata_2025 huggingface dataset:
The Spherical Interface. I. Thermodynamics
Authors: Buff Frank P.
Published: January 2005

An extension of the Gibbs thermodynamic theory of spherical interfaces leads to generalized forms for the Kelvin relation and the Gibbs adsorption equation. Quantities of physical interest are calculated in terms of the particular dividing surface making the superficial density of matter vanish, frequently more convenient than the surface of tension. An expression is proposed for the work required to form a droplet which is not in equilibrium with the surrounding vapor.
Solid Solutions of the Alkali Halides. II. The Theoretical Calculation of Lattice Constants, Heats of Mixing, and Distributions between Solid and Aqueous Phases
Authors: Durham George S. , Hawkins Janet A.
Published: January 2005

In all previous attempts to calculate interionic distances and heats of mixing for alkali-halide solid solutions, uniform anion-cation distances throughout a given solution have been postulated. In the present paper, the more logical assumption is made that the ions are not at a constant nearest-neighbor distance, but take up positions of minimum potential energy relative to one another. A method making use of the Born-Mayer-Huggins equation for the lattice energies of the alkali halides is developed for the determination of these positions in a simplified model and for the calculation of the potential energy associated with the resultant lattice. From these values, the average lattice constant, the heat of mixing, and the activity-coefficient ratio in the solid solution are calculated; from the latter is obtained the theoretical distribution ratio between solid and aqueous solutions. Values of the listed properties have been calculated at various mole fractions for the solid solutions KBr–KCl, RbBr–RbCl, RbCl–KCl, RbBr–KBr at 25° and have been found to be in good agreement with the experimental data available.
The Reactions of Methyl Radicals. III. The Abstraction of Hydrogen Atoms from Olefins
Authors: Trotman-Dickenson A. F. , Steacie E. W. R.
Published: January 2005

The abstraction of hydrogen atoms from eight olefins by deutero-methyl radicals formed in the photolysis of deutero-acetone has been investigated over a temperature range from 180°C to 340°C. The activation energies of those reactions have been determined relative to the activation energy of the combination of methyl radicals. The activation energies are 10.0 kcal for ethylene and 7.5±0.3 kcal for the other seven olefins. The collision theory ``P'' factors are all of the order of 10−3 or less.
The Mercury Photo-Sensitized Decomposition of Methyl Chloride
Authors: Masson C. R. , Steacie E. W. R.
Published: January 2005

A study has been made of the mercury photo-sensitized decomposition of methyl chloride over a pressure range of 10 mm to 640 mm, a temperature range of 72°C to 328°C, and a threefold variation in light intensity. The stoichiochemical equation for the reaction at 250°C and 160-mm pressure is 3CH3Cl=HCl+0.97CH4+0.49C2H4Cl2+0.41Hg2Cl2+0.24C2H4+0.18CH2=CHCl+0.15C+0.07C2H6+0.02H2+0.01C2H2. At high pressures, the following mechanism is shown to be consistent with the experimental results: Hg(63P1)+CH3Cl=Hg(61S0)+CH3+ClCH3+CH3Cl=CH4+CH2ClCl+CH3Cl=HCl+CH2ClCH2Cl+CH2Cl=C2H4Cl2Hg+CH2Cl=HgCl+CH2HgCl+HgCl  =Hg2Cl2CH2+CH2   =C2H4The first of these reactions is shown to have a quantum efficiency of unity. From the effect of added CO2 on the reaction, an approximate value of σ2=5.7×10−16 cm2 has been calculated for the quenching cross section of methyl chloride.
Electron Diffraction by Transmission through Thin Liquid Films
Authors: Lufcy Carroll W. , Palubinskas Felix S. , Maxwell Louis R.
Published: January 2005

Electron interference has been obtained by the transmission of 50-kv electrons through thin liquid films of the silicones: DC703, DC500, and DC200; and the hydrocarbons: octoil, castor oil, and glycerine. A commercial electron microscope (RCA, type EMU) was used after modification of the specimen holder. The electron diffraction patterns obtained from the hydrocarbons were all practically the same. They were characterized by three complete diffraction halos. The Bragg spacings (d) for octoil were found to be 4.93A, 2.26A, and 1.23A. These distances compare closely with values obtained previously for electron diffraction in liquid phytol (C20H39OH), Nujol, and Cenco pump oil. The patterns obtained for the silicones were significantly different from those of the hydrocarbons. Four complete rings were observed for DC703, giving d values of 8.17A, 4.18A, 1.97A, and 1.27A. The DC500 and DC200 fluids showed only three rings with Bragg spacings of 7.40A, 3.96A, and 1.27A; the ring which occurred at d=1.97A for DC703 was absent. The accepted Si–O distance of 1.60A is in agreement with the above data; however, the Si–O–Si–O angle is found to be approximately 104°. Such conclusions were confirmed by density calculations.
The Jones Reductor: A Model for the Kinetics of Chromatography
Authors: Knox Kerro , Thomas Henry C.
Published: January 2005

The Jones reductor can be made to assume a steady state of operation in the reduction of ferric sulfate. Its behavior under such conditions strongly indicates that the rate limiting process is the diffusion of ferric ion through a static film of solution around the solid particles. This is particularly evidenced by the exponential dependence of the extent of reduction on the square root of the flow rate. The behavior of the reductor as a function of zinc ion concentration, zinc amalgam particle size, and temperature, also agrees with this result.
Transport Properties of Gases with a Square-Well Molecular Interaction Potential
Authors: Holleran Eugene M. , Hulburt Hugh M.
Published: January 2005

The kinetic theory cross-section integrals are calculated for the square-well molecular potential model. Parameters are determined for light gases from viscosity measurements and are used to reproduce viscosity data for pure gases and binary mixtures.

Comparison is made between these parameters and those found from compressibility data and other transport properties. Different sets of parameters are apparently required for each transport property in order to account for the experimental results. The thermal diffusion constant for this model is a function of temperature and one other parameter. Excellent reproduction of the neon isotope data is obtained, and predictions of the qualitative behavior of the thermal diffusion ratio are made.
The Infrared and Raman Spectra of SiF4
Authors: Jones E. A. , Kirby-Smith J. S. , Woltz P. J. H. , Nielsen A. H.
Published: January 2005

The infrared and Raman spectra of SiF4 have been completely reexamined and extended. The Raman spectrum yields four lines at 268 cm−1, 390 cm−1, 800 cm−1, and 1010 cm−1, which have been assigned ν2, ν4, ν1, and ν3 respectively. In the infrared measurements, both prism and grating spectrometers were utilized. Several bands reported in earlier work have been ascribed to impurities and nine new bands have been observed and identified. The long-wave ν4 at 391 cm−1 has been observed with a KRS−5 prism and its envelope determined. Bands involving ν3 appear to have a PR spacing of about 12 cm−1 while those involving ν4 appear to have a PR spacing of about 20 cm−1.
The Role of Hybridization and Resonance in Molecular Structure
Authors: Duchesne Jules
Published: January 2005

It is shown that hybridization of the end-atoms in multiple-bonded molecules, as well as in single-bonded ones, is necessary for the understanding of the chemical bond properties. Resonance effects seem to play a minor role, except for conjugated systems.
A Two-Path Method for Measuring Flame Temperatures and Concentrations in Low Pressure Combustion Chambers
Authors: Penner S. S.
Published: January 2005

The two-path method for flame-temperature determinations has been extended to discrete radiators observed with instruments of arbitrary resolving power. Representative calculations of radiant intensity have been carried out for low pressure combustion flames in order to ascertain the feasibility of experimental study with standard spectroscopic instruments. It is shown how experimentally determined temperatures and emissivities can be utilized to calculate the concentrations of emitters, provided the emitting species is known and the radiation emitted corresponds to the thermodynamic equilibrium for the local conditions of temperature and pressure.
Thermomagnetic Investigations of Promoted and Unpromoted Iron Oxide and Iron Catalysts
Authors: Maxwell Louis R. , Smart J. Samuel , Brunauer Stephen
Published: January 2005

The Curie temperature (θ) and intensity of magnetization of certain unreduced and reduced iron oxide catalysts have been determined. For the singly promoted unreduced systems of Fe3O4 containing small amounts of one of the following, Na2O, K2O, Cs2O, BaO, B2O3, Al2O3, or SiO2, θ was found to be practically the same as for Fe3O4, but large reductions in the saturation intensity of magnetization (Is) were observed. The doubly promoted unreduced systems studied contained additions to Fe3O4 of Al2O3 and one of the following (in small amounts): Na2O, K2O, BaO, or SiO2. θ for these materials varied only slightly and was either equal to or less than that for Fe3O4. Large reductions in Is were found. Magnetic measurements on the reduced materials gave values of θ the same as for pure iron. The extent to which the promoters go into solid solution, both for the unreduced and reduced materials, is determined. Additional unreduced unpromoted iron oxides were investigated that had variable ratios (γ) of Fe++/Fe+++. Starting at γ=0.352, Is was found to increase with increasing γ to a maximum at γ=0.50, agreeing with the known value for magnetite, and then to decrease to a small value for large γ. The value found for Is at γ=0.352 is in agreement with Néel's theory of ``ferrimagnetism'' as applied to cubic Fe2O3 and Fe3O4. θ was found to be constant at about 583°C for γ from 0.352 to 1.276.
New Measurements on the Infrared Spectrum of F2O
Authors: Jones E. A. , Kirby-Smith J. S. , Woltz P. J. H. , Nielsen A. H.
Published: January 2005

The infrared spectrum of F2O has been re-examined from 2–25μ with a prism spectrometer and selected regions further examined with a grating spectrometer. Several bands observed by Hettner, Pholmann, and Schumacher have been shown to be caused by impurities. Other bands observed by them have been resolved, and an assignment of fundamental modes has been made which is consistent with dimensions of the molecule obtained from electron diffraction data. Two new bands have been observed and assigned to combinations of the fundamentals. The present observed frequencies and their assignments are: ν1=928 cm−1, ν2=461 cm−1, ν3=831 cm−1, ν1+ν3 and 2ν2+ν3 at 1731 cm−1, 3ν3=2460 cm−1, 2ν1+ν3=2643 cm−1.
The Bonding of Trihalide and Bifluoride Ions by the Molecular Orbital Method
Authors: Pimentel George C.
Published: January 2005

A simple molecular orbital treatment is presented to explain the bonding in trihalide ions, X3−, XY2−, and XYZ−, and bifluoride ion, HF2−. The M.O.'s are formed from linear combinations of npσ halogen orbitals, and the 1s hydrogen orbital and stable bonding M.O.'s are obtained without the introduction of higher atomic orbitals. Applications are suggested in prediction of other stable species and low energy reaction intermediates.
The Reaction of Methylcyclopentane with Hg 6(3P1) Atoms
Authors: Schlochauer M. , Gunning H. E.
Published: January 2005

The reaction of methylcyclopentane with photo-excited Hg 6(3P1) atoms was investigated in a static system at 29.35±0.01°C, over a range of initial pressures of 5–110 mm. After an initial slight pressure rise, the reaction exhibited a linear pressure decrease, the magnitude of which increased linearly with initial pressures of methylcyclopentane above 15 mm. The average rate of hydrogen formation also increased with initial pressure of methylcyclopentane and decreased with time in the course of a run. The products found were hydrogen, methylcyclopentenes, and a heavy fraction with the formula C12H22. Upon the basis of chemical and physical properties, strengthened by kinetic considerations, it was concluded that the C12H22 compound was predominantly dimethyldicyclopentyls. Quantum yields reached a maximum of 0.44 for hydrogen formation and 0.42 for methyl-cyclopentane consumption.

The mechanism postulated proceeds through an initial carbon-hydrogen bond split, thus: (1)  cyclo C6H12+Hg 6(3P1)  →cyclo C6H11+H+Hg 6(1S0)(2)  H    +cyclo C6H12→H2    +cyclo C6H11(3)  H    +cyclo C6H11→cyclo C6H12(4)  H    +cyclo C6H11→cyclo C6H10+H2(5)  cyclo C6H11+cyclo C6H11→C12H22(6)  H2    +Hg 6(3P1)  →H+H+Hg 6(1S0)

This mechanism yields rate expressions which confirm the trends observed in the experimental work.
The Growth of Uniform Colloidal Dispersions
Authors: Reiss Howard
Published: January 2005

Recently, much interest has been focused upon the preparation of monodispersed colloids using the ``growth by diffusion'' process. Although these colloids are useful tools in experimental procedures, no well-established reason has been given to explain why the ``growth by diffusion'' method should produce such uniform dispersions. In this paper it is shown that an assembly of competing particles, growing by diffusion, develop the squares of their radii at equal rates. This condition provides a mechanism leading towards uniformity.

A method, based on this equal square rule, is suggested for the determination of size distributions in polydispersed systems.
Note on Frequency Spectra of Simple Solids from Specific Heat Data
Authors: Katz E.
Published: January 2005

If the specific heat C(T) of a solid is given as a function of temperature from T=0 to ∞ with infinite accuracy, the frequency spectrum f(ν) is uniquely determined. What information about f(ν) can be derived from specific heat data of experimental accuracy? The following conclusions give the answer.

(1) Experimental specific heats determine accurately the low frequency part of the frequency spectrum but allow a latitude, wide enought to fit almost any theory, for its high frequency part.

(2) In a Debye plot (effective Debye temperature θ versus T) peaks and dips in the region 0<T<θ/10 represent dips and peaks in the low frequency part of the frequency spectrum. The correspondence is so simple that it can be interpreted at a glance. The peaks and dips are superimposed on a simple Debye spectrum and presumably have a direct physical meaning, in terms of lattice irregularities. Only their centers and total weights are obtainable, so that they act effectively as single Einstein frequencies.

(3) In the region θ/5<T<∞ all information obtainable about f(ν) consists of the first few even moments (three for specific heat errors of order one percent, five for 0.1 percent). These can be represented respectively by two or three weighted equivalent Einstein functions without direct physical meaning.

(4) The region θ/10<T<θ/5 corresponds to the high frequency part of the frequency spectrum, but hardly any information can be derived here.
LCAO Self-Consistent Field Calculation of the Twisting Frequency and π-Electron Energy Levels of Allene
Authors: Parr Robert G. , Taylor G. Russell
Published: January 2005

The twisting frequency of allene is computed by the nonempirical method of antisymmetrized products of molecular orbitals in self-consistent field LCAO approximation, as applied to the four unsaturation electrons of the molecule, molecular orbitals for these electrons being taken as linear combinations of 2p Slater atomic orbitals. By comparison with a previous calculation by the same method on ethylene, the ratio of the twisting frequency of ethylene to the twisting frequency of allene is computed to be 1.7, sensibly independent of the effective charge in the atomic orbitals, which is the only extrageometrical parameter entering the theoretical calculations. The first ionization potential of allene is predicted to be 10.4 ev and the mean of the first allowed singlet electronic absorption band and the corresponding triplet is predicted to lie at 5.1 ev.
On the Energetic Treatment of Non-Isothermal Processes. The Principle of Thermal Interaction
Authors: Holtan Hans
Published: January 2005

1. The existing theories for non-isothermal processes are discussed. They can be divided into two kinds, depending upon whether or not they take the flow of heat into account. None are able to predict experimental results.

2. A new hypothesis, ``the principle of thermal interaction'' is introduced by employing Onsager's principle of reciprocity and is expressed in terms of Br⊘nsted's energetics.

It states that there is an interaction between the flow of heat and the transport phenomena in a non-isothermal process in such a way that the loss of work (loss of potential energy) for the transport of entropy bound to chemical substance can be compensated partly or completely by the transport of free entropy contained in the flow of heat in the opposite direction. The result is that any particle will tend to move against the temperature gradient.

3. The new principle is applied to thermocells with a solid electrolyte, and the results predicted are shown to be in agreement with experimental data.

4. The Knudsen equation, applicable to a thermal transpiration cell, is derived without employing the kinetic theory of gases.
Molecular Orbital Calculations for H3
Authors: Walsh J. M. , Matsen F. A.
Published: January 2005

Calculations are made on the binding energy of H3 using the several methods of calculation based on molecular orbitals. The results are compared to the valence bond-plus-ionic-terms treatment of Hirschfelder et al., which employs the most general linear combination of products of atomic orbitals. The antisymmetrized molecular orbital treatment with configuration interaction is only slightly inferior to this treatment, while the other molecular orbital calculations are considerably inferior. These conclusions probably apply to calculations on more complex molecules.
The Infrared Spectrum of Sulfur Hexafluoride
Authors: Lagemann R. T. , Jones E. A.
Published: January 2005

The infrared absorption spectrum of gaseous SF6 has been investigated from 2 to 25μ with prism spectrometers of high resolution. The frequencies of the infrared active fundamentals found by earlier workers have been confirmed with the exception of one, formerly found at 965 cm−1, which is shown to be at 940 cm−1. However, the remainder of the spectrum differs considerably from previous work. With the aid of the Raman data, the observed spectrum has been interpreted in detail.
The Calculation of Diffusion Coefficients from Sorption Data
Authors: Prager Stephen
Published: January 2005

A method is described for the calculation of the dependence of the diffusion coefficient on the concentration of diffusing material from data obtained by studying the rates of sorption of vapors by films. The principle of the method is to approximate the actual concentration dependence by a step function. For such a function the differential equations involved can be solved analytically, and the heights of the individual steps can be computed; the step function is then smoothed out by an averaging process. The method has been tried out for the sorption of isobutane by polyisobutylene at 35°C and found to be quite satisfactory.
An Interferometric Method of Determining Diffusion Coefficients in Gaseous Systems
Authors: Boyd Charles A. , Stein Norman , Steingrimsson Virginia , Rumpel William F.
Published: January 2005

This paper describes a new type of experimental method for accurately measuring diffusion coefficients in gaseous systems.

The change of composition in the diffusion cell is followed by measuring the change in refractive index with an interferometer. Results obtained using this method compare favorably with some values reported in the earlier literature. In addition, values are reported for new systems not studied previously. A comparison is made between measured values and those calculated from viscosity data.
Tripyramidal Bond Orbitals
Authors: Duffey George H.
Published: January 2005

Three nine-bond arrangements which are not forbidden in spd hybridization are described. Of these, the tripyramidal arrangement is discussed in detail since it seems most favorable stericly. In this arrangement there are two types of orbitals, six trigonal prism orbitals and three equatorial orbitals. When the average orbital strength is greatest, it equals 2.983. Some light is thrown on the following structures: TaF7−2, OsF8, and conjectural OsF9−.
The Vibrational Spectra of Molecules and Complex Ions in Crystals. V. Ammonia and Deutero-Ammonia
Authors: Reding F. P. , Hornig D. F.
Published: January 2005

Infrared spectra of thin non-scattering films of NH3 and ND3 were obtained at −190°C. All four fundamentals of both compounds were observed with no evidence of inversion doubling of ν2. The crystal spectrum of NH3 suggests a frequency near 3450 cm−1 for ν3 in the gas. The spectra are in agreement with a molecular crystal having the reported x-ray symmetry T4. Two of the five torsional lattice vibrations were probably observed directly and one more strongly indicated in combination bands. A fourth lattice frequency of 53 cm−1 also occurs in combination bands. Since the coupling between the various internal vibrations and between the lattice and internal vibrations proved to be small, the potential function of the crystal was assumed to be separable into an internal and a lattice problem. A normal coordinate treatment of the internal vibrations fits all frequencies to better than one percent.
The Effect of Temperature on the Photolysis of Methylamine
Authors: Johnson Clarence I. , Taylor H. Austin
Published: January 2005

The photolysis of methylamine has been investigated with the purpose of determining the effect of temperature. To minimize the interference due to polymeric liquid formation, the reaction was studied from −15° to 30°C. The energy of activation of amine disappearance was found to be 6 kcal, a minimum value, but which is probably caused by the effect of temperature on the light absorption. The possibility of ethylene diamine as an intermediate undergoing further decomposition or a polymerization-condensation reaction evolving ammonia is considered. The rates of hydrogen and ammonia production show previously postulated mechanisms to be untenable.
Time Lag in the Self-Nucleation of a Supersaturated Vapor
Authors: Probstein Ronald F.
Published: January 2005

Recent experiments have indicated that the quasi-equilibrium Volmer theory of self-nucleation fails in some cases to predict when the condensation of water vapor or the components of air will occur in the very rapid vapor expansions in a supersonic wind tunnel. By the obtaining of an approximate solution to the non-steady Becker-Döring equation for the self-nucleation of a super-saturated vapor, an attempt has been made to determine whether the time lag associated with the approach to the steady state rate of formation of condensation nuclei could account for the discrepancies between theory and experiment. A similar calculation, where the work required to form embryos of the condensing phase was neglected, has been carried out by Kantrowitz. In the present paper the work term has been taken into account to a first approximation. Also considered is the time lag arising from the heating of the nuclei due to bombardment by molecules of the condensing phase as well as the time lag resulting from an accommodation coefficient for the liquid nuclei different from unity.

Calculations of the self-nucleation of water vapor in air and nitrogen in air have been carried out. From the results it appears that the build-up time is not appreciably lengthened by inclusion of the work term to a first approximation. The results also indicate that, unless the accommodation coefficient should have a value much lower than what appears to be reasonable from meager experimental evidence, the time lag alone could not account for the existing discrepancies between theory and experiment.
Partition Functions of Cubic Lattices
Authors: Fisher E.
Published: January 2005

The Born-von Kármán theory of vibrational specific heats is given an analytical development that is adequate for computation even at low temperatures. Application is made to simple, body-centered, and face-centered cubic lattices.
Interpretation of the Data on the Thermal Decomposition of Nitrous Oxide
Authors: Johnston Harold S.
Published: January 2005

The data on the thermal decomposition of nitrous oxide, which as they stand are anomalous in many respects, are examined. It is found at low concentrations of nitrous oxide that a heterogeneous first-order reaction of low energy of activation becomes important. Correction of all data for this heterogeneous reaction removes most of the anomalous spread of values of the energy of activation which had varied from 48 to 65 kcal per mole. The energy of activation at the low concentration limit is 59 kcal per mole, which gives normal pre-exponential factors and ``number of oscillators.'' The data, corrected for heterogeneity, are those for a straightforward unimolecular reaction, giving the low concentration limit and approaching the high concentration limit. By empirical modification of existing theories specific rate constants are found for the variously excited molecules which give a good description of the observed curve of log rate-constant vs log-concentration. The function of specific rate constants vs energy of the molecule is closely related to the continuous form proposed by Rice and Ramsperger, who assume four effective oscillators, which is the number of normal modes of vibration of the nitrous oxide molecule. More experimental work is needed on this kinetic system.
Methyl Radical Induced Polymerization of Gaseous Butadiene
Authors: Volman David H.
Published: January 2005

Free methyl radicals from thermally decomposing di-t-butyl peroxide were used to initiate the polymerization of gaseous butadiene. The rate of polymerization was found to follow the equation —d[M]/dt = kp(ki/kt)½[M][C]½, where kp, ki, and kt refer to the rate constants for propagation, initiation, and termination, respectively; M and C refer to butadiene and peroxide. From the effect of temperature on the over-all rate constant and the known values of Ei and Et, the value of Ep, the activation energy for chain propagation, was found to be 2.6 kcal/mole.
The Microwave Spectra, Structure, and Dipole Moments of Ethylene Oxide and Ethylene Sulfide
Authors: Cunningham George L. , Boyd A. W. , Myers Rollie J. , Gwinn William D. , Le Van W. I.
Published: January 2005

The microwave spectra of C212H4O, C12C13H4O, C212D4O, C212H4S32, C212H4S34, and C212D4S32 have been determined. For each isotopic species three moments of inertia are obtained. From the 9 moments of inertia for each compound, a set of ``effective'' bond distances and angles (5 in number) have been selected. These ``effective'' bond distances are all self consistent to 0.002A or better. A brief discussion of the resulting structure is given. The dipole moments of C2H4O and C2H4S were determined from the magnitude of the Stark splitting.
Energy Transfer by Collision in Benzene Vapor
Authors: Cheng Laura M.
Published: January 2005

The velocity and absorption of ultrasonic waves in benzene vapor were measured by means of the sonic interferometer, at frequencies of 251.44 kc, 497.44 kc, and 1008.06 kc, within the pressure range 2 to 9.5 cm Hg, between the temperature limits 30.2°C to 37.6°C. Dispersion of the velocity, after being reduced to 30°C, ranged from 190.4 m/sec to 207.31 m/sec. The corresponding values of the specific heat Cv/R dropped from 9.45 to 3.0. Values of the molecular absorption coefficients, which are several times larger than the classical ones, are interpreted as due to the loss of vibrational degrees of freedom only. The theoretical values calculated from Kneser's method, show a close agreement with the dispersion curve, but not so well with the absorption values. An improvement of fit was made by the assumption of two relaxation times, but owing to the scattering of the experimental points, it is very hard to decide which theory fits better. The value of the single relaxation time is 5×10−8 sec, and those from the second assumption are 2×10−8 sec and 6.8×10−8 sec.
Raman Spectra of Several Compounds Containing Phosphorus
Authors: Hanwick T. J. , Hoffmann P. O.
Published: January 2005

Raman spectra of water solutions of NaH2PO2, KH2PO2, HPO3, NaPO3, K4P2O7, K2Na2P2O7, K2H2P2O7, and Na2H2P2O7 were photographed using a Hilger constant-deviation spectrograph. Illumination was provided by four Hanovia mercury lamps, the 4358A line being used as the exciting radiation. A system of liquid filters reduced the effect of the other mercury lines so that their presence was not objectionable. A Wollaston prism made possible the separation of the perpendicular and parallel components of the scattered radiation. Intensity and depolarization values were calculated from traces obtained by means of a Kipp and Zonen microphotometer. The Raman spectra of the NaH2PO2 and KH2PO2 solutions were identical, while those of the HPO3 and NaPO3 solutions differed markedly from each other. The spectra of the four pyrophosphate solutions were all similar in appearance, and their spectral lines showed similar relative intensities and depolarization values. Suggested models have been postulated.
Triple-Dipole Interaction. II. Cohesion in Crystals of the Rare Gases
Authors: Axilrod B. M.
Published: January 2005

The dependence of the triple-interaction between three neutral atoms on the configuration of the latter suggests a possible explanation of the structure of the crystals of Ne, A, Kr, and Xe. The latter crystallize in the face-centered cubic (f.c.c.) lattice, one of the two closest-packed structures, the other being the hexagonal closest-packed. The triple-dipole interaction was directly summed in both the f.c.c. and h.c.p. lattices for a cylindrical region whose radius and semi-altitude were about three times the nearest-neighbor distance.

The calculations, which were made on IBM punched-card machines, are outlined. The triple-dipole interaction amounts to two to nine percent of the cohesive energy for the crystals of the above rare gases. The difference in the triple-dipole interaction for the f.c.c. and h.c.p. lattice, although favoring the former structure, is less than 0.01 percent of the cohesive energy and hence cannot account for the structure of these rare gas solids.
Gaseous Diffusion as a Random Process
Authors: Furry W. H. , Pitkanen P. H.
Published: January 2005

It has long been known that the problem of random flights of a single molecule provides in principle a method for calculating the diffusion coefficient D12 for the case in which the concentration of the diffusing component is small. This method has been, in effect, an elementary and rather crude one, because correlations of speed and direction were not taken into account and, accordingly, the rather ambiguous concept of mean free path had to be given an arbitrary definition. In this paper we overcome these difficulties and give an accurate treatment of gaseous diffusion based on the random flight method. The determination of the diffusion coefficient is made to depend on the solution of an integral equation; the unknown function of this equation can be interpreted as the unambiguously defined effective mean free path, for diffusion, of molecules of given speed. The resulting value of D12 is the same as is obtained from the standard Enskog-Chapman treatment based on Boltzmann's equation.
The Vapor Pressure of Zinc in the Range 300°—360°C
Authors: Vance John E. , Whitman Charles I.
Published: January 2005

The vapor pressure of zinc has been measured using Knudsen's effusion method. The temperature-vapor pressure relation was found to be log10pmm=(−6688/T)+8.888 in the range 300°—360°C. These results are about 20 percent higher than those previously reported. It is suggested that this difference may be attributed principally to the omission of a probability factor by earlier workers.
Transference Numbers for Sodium and Potassium Chlorides in Anhydrous Methanol at 25°C
Authors: Davies J. A. , Kay R. L. , Gordon A. R.
Published: January 2005

Transference numbers have been determined by the moving boundary method for sodium chloride in anhydrous methanol at concentrations from 0.003 N to 0.01 N, and for potassium chloride at concentrations from 0.005 N to 0.02 N. Autogenic cells were used for cation boundaries and sheared cells (with paratoluenesulfonate, di- and triiodobenzoate as indicator ions) for anion boundaries. The results are comparable in precision with those for aqueous solutions and satisfy all criteria for transference data. The Longsworth function is linear in the concentration up to 0.01 N, thus making it possible for the first time to obtain precise limiting transference numbers in an anhydrous solvent.
Substituted Stilbenes. I. Absorption Spectra
Authors: Calvin Melvin , Alter H. Ward
Published: January 2005

The absorption spectra of five pairs of cis-trans isomers of substituted stilbenes have been measured. The spectra of the geometrical isomers of p-amino p′-nitro stilbene hydrochloride are compared with those obtained by previous work.
The Effects of Added Chlorides on the Absorption Spectra of Cobaltous Chloride in Water and in Formamide
Authors: Dawson Lyle R. , Chaudet Julian H.
Published: January 2005

It has been shown that alkali and alkaline earth chlorides widen, intensify, and shift the absorption bands in the spectrum of cobalt chloride in water and in formamide. These effects appear to be directly related to the solvating power of the added cation. An interpretation of the observed phenomena has been presented on the basis of desolvation of the cobalt ion followed by interaction with chloride ions within the solution. In addition, probable mechanisms for the formation of the chloride complex and the resultant changes in the color characteristics of the solution have been suggested. Reversals of the expected order of the effects of sodium and potassium salts in water and of calcium and strontium salts in formamide have been shown.
Bromination of Hydrocarbons. IV. Photochemical and Thermal Bromination of Neopentane in the Gas Phase. The C–H Bond Strength in Neopentane
Authors: Hormats Ellis I. , Van Artsdalen Ervin R.
Published: January 2005

The homogeneous photochemical bromination of neopentane was studied in the temperature range 98° to 152°C and found to proceed through an atom and radical chain mechanism analogous to the bromination of methane and ethane. Hydrogen bromide inhibits photobromination of neopentane much more than it does in the case of methane, increasing in its effect with rising temperature. Thermal bromination was studied at 197°C and found to take place by a mechanism analogous to the photochemical reaction, the bromine atoms being produced thermally rather than photochemically. The corrected activation energy of the overall reaction was determined from the temperature coefficient of the photochemical reaction and found to be 17.8 kcal/mole. Questions of the efficiencies of various molecules as third bodies in the homogeneous recombination of bromine atoms and problems relating to steric effects in atom and radical reactions have been discussed. The C–H bond strength in neopentane has been estimated to be 95.5 kcal/mole at room temperature.
The Contribution of Thermal Conductivity to the Ultrasonic Absorption Coefficient in Liquefied Gases
Authors: Beyer Robert T.
Published: January 2005

The contribution of thermal conductivity to ultrasonic absorption in liquefied gases is computed on the basis of known experimental values of the thermal conductivity or of approximate theoretical values. The results are compared with Galt's experimental data and satisfactory agreement is obtained.
Quantitative Infrared Intensity Measurements. I. Carbon Monoxide Pressurized with Infrared-Inactive Gases
Authors: Penner S. S. , Weber D.
Published: January 2005

Quantitative infrared intensity measurements on CO pressurized with H2, He, A, O2, and N2 for total pressures up to 700 psia have been carried out. The values of integrated absorption for the fundamental and first overtone of CO have been found to be 237 cm−2 atmos−1 and 1.64 cm−2 atmos−1, respectively. The numerical values of integrated absorption were obtained by using an indirect method for the interpretation of experimental data, similar to the extrapolation technique of Wilson and Wells.

The experimental data obtained at very large values of the total pressure should yield correctly the numerical values of the spectral absorption coefficients. This statement is supported by the fact that the integral over the spectral absorption coefficients at a total pressure of 700 psia yields values for the integrated absorption of fundamental and first overtone of CO which are in excellent agreement with results obtained by indirect methods.
Compressibility of Gases at Pressures up to 50 Atmospheres. V. Carbon Tetrafluoride in the Temperature Range 0°—400°C. VI. Sulfur Hexafluoride in the Temperature Range 0°—250°C
Authors: MacCormack K. E. , Schneider W. G.
Published: January 2005

The gaseous compressibilities of carbon tetrafluoride in the temperature range 0–400°C, and sulfur hexafluoride in the temperature range 0–250°C have been measured at pressures up to 50 atmospheres by a method employing gas expansion. The data have been fitted to a series equation of the type, PV (Amagat units)=AT+BTP+CTP2+DTP4,and the virial coefficients are tabulated.
Intermolecular Potentials. I. Carbon Tetrafluoride and Sulfur Hexafluoride. II. Carbon Dioxide
Authors: MacCormack K. E. , Schneider W. G.
Published: January 2005

Experimental second virial coefficient data for carbon tetrafluoride, sulfur hexafluoride, and carbon dioxide have been used to investigate the intermolecular potentials of these molecules on the basis of a Lennard-Jones model. Force constants for the fluoride molecules can be fitted rather satisfactorily, but the constants so derived do not agree with those derived from other gaseous properties, e.g., the critical data. This result may be due to the assumption of central forces for the symmetrical fluoride molecules.

For carbon dioxide it was found that the derived force constants varied with temperature, the high temperature data yielding lower values of the collision diameter r0. The results can be interpreted on the basis of a partial association. A likely configuration for the resulting dimer is suggested.
Kinetics of OH Radicals from Flame Emission Spectra. III. Total Transition Probabilities and the Energetic Distribution of OH(2Σ+) and O2(3Σu−) in the Oxy-Hydrogen Flame
Authors: Shuler Kurt E.
Published: January 2005

The energetic distribution of OH(2Σ+) and O2(3Σu−) in hydrogen-oxygen flames has been investigated. The measurements were made in the inner cones of these flames burning with various fuel ratios (lean, stoichiometric, and rich) at atmospheric pressure. The relative concentrations of the excited species were determined by comparing the calculated equilibrium intensity ratios of OH(2Σ+) and O2(3Σu−) with the experimental intensity ratios. The electronic, vibrational, and rotational transition moments relevant to this calculation have been computed. The good agreement between the experimental intensity ratios and the calculated equilibrium intensity ratios indicates that the electronically excited O2(3Σu−) is in thermal equilibrium with OH(2Σ+). It is possible, therefore, that O2 is excited thermally in the hydrogen-oxygen flame.
Dissociation Energies of the Cd++ Vacancy Complex and of the Double Vacancy in Sodium Chloride
Authors: Reitz John R. , Gammel J. L.
Published: January 2005

Dissociation energies for two types of lattice imperfection (namely, the impurity ion vacancy complex and the double vacancy) have been determined theoretically for NaCl, using the semiclassical model of ionic crystals developed by Born and Mayer. The procedure followed in calculating these energies was based on the method developed by Mott and Littleton for computing the formation energies of single vacancies. The numerical results which were obtained are 0.44 ev and 0.89 ev for the dissociation energies of the complex and double vacancy, respectively.
Orthonormal Sets of LCAO Molecular Orbitals for Second-Row Homopolar Diatomic Molecules
Authors: Mulliken Robert S.
Published: January 2005

The forms of the LCAO MO's (molecular orbitals approximated by linear combinations of atomic orbitals) of any homopolar second-row diatomic molecule are studied under the restriction that they shall form an orthogonal set. The requirement of orthogonality per se causes 1s−2s−2pσ hybridization (forced hybridization) among the AO's (atomic orbitals) used in constructing the LCAO's. Equations, tables, and figures are given showing how the degrees of hybridization in the members of mutually orthogonal sets of σg LCAO MO's, likewise of σu LCAO MO's, are related, as a function of two parameters: (a) assumed degree of hybridization in any one member of the set; (b) a parameter proportional to interatomic distance times effective nuclear charge. This is done using primarily Slater AO's, but the effect of using SCF (self-consistent-field) AO's is also studied.

Assuming that overlap integrals are good measures of bond strengths, it is shown that the effect of forced hybridization is to diminish bond strengths. It is concluded that this bond-weakening effect in LCAO MO valence theory is the counterpart of certain exchange repulsions which appear in the Heitler-London valence bond theory, namely those between bonding electrons on one atom and electrons in different (either bonding or lone-pair) AO's on the other atom. The procedure used promises to give a good measure of the strengths of inner shell-outer shell interatomic repulsions; it tends to indicate that these are, in general, not large but not negligible. A paradox resulting from forced hybridization is touched on and more or less resolved; this paradox has to do with the method of counting the numbers of s and pσ electrons per atom in a molecule described by LCAO methods.
The Microwave Spectrum of Sulfur Dioxide
Authors: Sirvetz M. H.
Published: January 2005

The K-band microwave spectrum of sulfur dioxide has been reinvestigated with results which are in agreement with the main points of the previously reported analysis by Dailey, Golden, and Wilson. Some additional lines have been assigned, and new rotational constants have been derived which permit considerably closer agreement between observed and computed frequencies. From two of these the structural parameters r(S–O) = 1.432A and ≰ (O–S–O) = 119.53° can be obtained. The remaining discrepancy (of the order of 15 mc for ten lines involving J values up to J = 35) has been attributed to inaccuracies in the centrifugal distortion computation.
Intensities of Some Characteristic Infrared Bands of Ketones and Esters
Authors: Francis S. A.
Published: January 2005

Integrated intensities of the 2900, 1720, 1460, 1370, and 1200 cm−1 bands are reported for four ketones and five esters, and grating spectra are shown for the 2780–3060 and 1300–1500 cm−1 spectral regions. CH3 and CH2 structural group integrated intensities are derived from the data which are adequate for predicting the integrated molecular intensities of the bands in the 2900, 1460, and 1370 cm−1 spectral regions. The data show that the carbonyl and ester structural groups reduce the intensities of the stretching modes and increase the intensities of the deformation modes of adjacent CH3 and CH2 groups. A number of empirical correlations are pointed out between positions of absorption maxima in the 2900, 1460, and 1370 cm−1 regions and the internal molecular environment of CH3 and CH2 groups.
The Vapor Pressure and Critical Constants of Neopentane
Authors: Beattie James A. , Douslin Donald R. , Levine Samuel W.
Published: January 2005

The vapor pressure of neopentane has been measured from 50° to the critical point. The equation, log10p(atmos)=3.901633−1136.462T+4.99118×10−4T  (T=t∘C+273.16),gives a fair representation of the observations.

A study of the compressibility of neopentane in the critical region gives for the critical temperature, pressure, volume, and density the values: tc = 160.60°±0.05°C (Int.), pc = 31.57±0.03 normal atmospheres, Vc = 0.303 liter per mole (4.20 ml per g), dc = 3.30 mole/liter (0.238 g per ml). The uncertainty in the critical volume and density is 1 percent.
The Limiting Negative Pressure of Acetic Acid, Benzene, Aniline, Carbon Tetrachloride, and Chloroform
Authors: Briggs Lyman J.
Published: January 2005

The limiting negative pressure of acetic acid, benzene, aniline, carbon tetrachloride, and chloroform has been measured in relation to temperature. A centrifugal method was employed, the liquid being contained in a capillary tube, the ends or legs of which were bent sharply back parallel to the straight central part. The tube was cemented to a horizontal spinner, with its midpoint intersecting the spin axis. Both ends of the tube were open, which facilitated filling and cleaning. The volume of liquid was so chosen that the menisci were located in the legs of the tube near the bends.

The maximum values observed were: CH3COOH, −288 bars; C6H6, −150 bars; C6H5NH2, −300 bars; CCl4, −276 bars; CHCl3, −317 bars. Excepting benzene, the limiting negative pressure of these liquids has not heretofore been measured. All except benzene equal or exceed that of water (−275 bars). Acetic acid, benzene, and aniline show a decrease in the limiting negative pressure as the freezing point is approached, like water, but the effect is much less marked.

The higher values observed for the polar liquids in comparison with their nonpolar relatives suggests that the dipoles are contributing markedly to the cohesion of the liquid. An investigation of the cis- and trans-forms of the same liquid is now under way.
Contribution to the Theory of Critical Phenomena
Authors: Zimm Bruno H.
Published: January 2005

If one considers the critical point between the liquid and gaseous phases, it may be shown that the ``principle of superposition'' leads to the result that the critical point is a singularity in the isotherm of fugacity or pressure against density. At this singularity the derivatives of every order of the fugacity or pressure with respect to the density are zero, not only the first two derivatives as in the van der Waals theory. It is postulated that these relations are true despite the uncertain nature of the superposition approximation.

If the critical point is such a singular point, it can be shown that Mayer's theory of critical phenomena leads quite reasonably to a single characteristic temperature instead of two separate temperatures for the vanishing of the slope of the isotherm and for the appearance of a surface tension. Experimental observations on the anomalous shape of the isotherms near the critical point are in accord with the theory.
Bromination of Hydrocarbons. V. Neopentane and Hydrogen Chain Lengths. Efficiency of Neopentane as a Third Body
Authors: Schweitzer Francis E. , Van Artsdalen Ervin R.
Published: January 2005

A direct comparison of the rates of photochemical bromination of neopentane and hydrogen has been made, which shows the neopentane reaction to be 94 times faster at 470.6°K. It is shown that neopentane is of the order of 175 times more effective than hydrogen in promoting homogeneous bromine atom recombination. An estimate of the chain lengths for both photo and thermal bromination has been made, and it appears definite that the chain with neopentane has several hundred links. It is suggested that this is in part the result of a high radical concentration, favored by the fact that the heat of formation of neopentyl radical is only very slightly endothermic as contrasted with that for methyl radical or hydrogen atom.