bluuebunny/crossref_metadata_2025 huggingface dataset:
The Absolute Rates of Reaction of Hydrogen with the Halogens
Authors: Wheeler A. , Topley B. , Eyring H.
Published: January 2005

In this paper we apply the statistical-mechanical method which has only recently been developed for reaction rates to three new groups of reactions. These are the reactions of I2, Cl and Br with the various kinds of hydrogen molecules. In the first type (I2+H2→2HI) symmetry properties enable one to divide the six internal modes of vibrations for the four coplanar atoms into three sets with one, two and three modes of vibration in each so that in obtaining the frequency nothing greater than a cubic is solved. This treatment of the frequencies will apply to a very broad class of reactions. The potential surfaces probably yield too high a zero-point energy for the activated state. In spite of this result they give the right relative rates for the various isotopic reactions because mass enters very strongly into what in the past has been thought of as the collision factor. The study of isotopic reactions in conjunction with the new theory of rates gives a detailed knowledge of the potential in the activated state and can be carried much farther than has been done in this preliminary treatment. The treatment has been carried far enough however to show its general applicability to these types of processes.
The Heitler-London Repulsive State of Hydrogen
Authors: James Hubert M. , Coolidge Albert Sprague , Present Richard D.
Published: January 2005

A variational method has been used in the study of the 1sσ2pσ 3Σu state of H2. Two independent computations with formally different functions gave, for a nuclear separation of 1.5aH, energies which agreed to within 0.03 ev and functions with a root-mean-square fractional difference of about 2 percent. A study of the way in which the computed energies converged to a limit, as the complexity of the varied functions was increased, indicates that the interaction energy of the atoms at this distance is +5.145±0.02 ev. Computations were also made for nuclear separations of 1.6 aH and 1.87 aH. A potential curve passed through points thus determined and approaching the Heitler-London curve asymptotically for large nuclear separations is believed to be accurate to 0.2 ev for nuclear separations greater than 1.35 aH. This curve is compared with the results of previous computations and the curve constructed by Finkelnburg and Weizel to account for the variation with wave-length of the excitation potential of the continuous spectrum. Discussion of the disagreement with the results of Finkelnburg and Weizel is deferred to a later paper.
X-Ray Diffraction Intensity of the Two Liquid Phases of Para-Azoxyanisol
Authors: Stewart G. W.
Published: January 2005

Further experiments with greatly improved conditions show that the liquid crystal swarms or groups of molecules at 125°C give an x-ray diffraction intensity distribution curve which is similar to but not exactly like that of the transparent liquid at 150°C. The former has a greater intensity at the peak, and a narrower peak with a steeper slope on the zero angle side. The group in the liquid crystal, about 106 molecules, does not have the same structure as the very much smaller and less stable cybotactic group in the liquid. The latter does not need to contain more than 25 to 50 molecules to account for the experimental evidence. The liquid crystal swarms may be descriptively regarded as a regimentation of modified cybotactic groups. A new temperature effect is strongly suggested by the apparent orientation of swarms in the liquid crystal with molecular axes perpendicular to the temperature gradient.
The Vibration-Rotation Energy Levels of Polyatomic Molecules I. Mathematical Theory of Semirigid Asymmetrical Top Molecules
Authors: Wilson E. Bright , Howard J. B.
Published: January 2005

The exact classical kinetic energy for a system of point masses is obtained. From this the correct form for the quantum-mechanical Hamiltonian operator is derived. If the assumption of small vibrations is applied to this operator, the familiar approximation of a rigid top plus normal coordinate vibrator is obtained. In order to secure better approximations, in which larger amplitudes of vibration are admitted, a perturbation method is introduced which permits the change of moment of inertia with vibration, the coupling of rotation and vibration, and the centrifugal stretching effects to be taken into account. If the stretching terms alone are neglected, it is possible to reduce the secular equation for the rotational energy levels to the Wang form, except that ``effective moments of inertia'' must be used whose magnitude depends on the vibrational quantum state. The relation of these quantities to the equilibrium moments of inertia or to the instantaneous moments of inertia averaged over the vibrational motion is not simple, although the numerical deviation from them may not be great. In addition, for molecules with less than orthorhombic symmetry there is the further possibility that the orientation of the principal axes of inertia will vary with the vibrational quantum number. It is also pointed out that the Wang equation should not fit the data when a nearby vibrational state perturbs the state under examination or when the centrifugal effects are large. A method is indicated whereby the latter terms may in principle be calculated.
The Application of the Three-Dimensional Patterson Method and the Crystal Structures of Proustite, Ag3AsS3, and Pyrargyrite, Ag3SbS3
Authors: Harker David
Published: January 2005

It is shown that the three-dimensional Patterson method can be so simplified by the use of the symmetry properties of the crystal under consideration that its use in determining the positions of atoms in crystals is practicable. This method is then used to determine the positions of the heavy atoms in proustite, Ag3AsS3. The positions of the sulfur atoms are found by the use of the covalent atomic radii and assumptions concerning bond directions. The structure so derived is found to be compatible with the observed data. Proustite is found to contain pyramidal AsS3′′′ groups and silver atoms forming two bonds to sulfur in almost opposed directions. Pyrargyrite, Ag3SbS3, is found to have almost the same structure as proustite. The analytical statement of the structures is as follows:— The space group, C3v6 — R3c, is common to both proustite and pyrargyrite. The special positions of C3v6 are (in hexagonal axes) (2a)0,0,Z;0,0,12+Z;(6b)X,Y,Z;Y¯,X−Y,Z;Y−X,X¯,Z;Y¯,X¯,12+Z;X,X−Y,12+Z;Y−X,Y,12+Z;and positions derived from these by the operations of the rhombohedral lattice. The parameter values are: ProustitePyrargyritea0=10.74A,c0=8.64Aa0=11.04A,c0=8.71A2As in 2a,ZAs=0.0002Sb in 2a,ZSb=0.0006Ag in 6b,XAg=0.2466Ag in 6b,XAg=0.250YAg=0.298YAg=0.305ZAg=0.235ZAg=0.2106S in 6b,XS=0.2206S in 6b,XS=0.220YS=0.095YS=0.105ZS=0.385ZS=0.355
The Raman Spectra of the Deuteromethanes
Authors: MacWood George E. , Urey Harold C.
Published: January 2005

The four deuteromethanes were prepared. Their vibrational Raman spectra were photographed under high dispersion. A total of 20 lines were analyzed. A discussion, in the light of the general theory, is given of a sequence of observed overtones.
Absorbing and Reflecting Powers of H2SO4 Solutions in the Far Infrared
Authors: Cartwright C. Hawley
Published: January 2005

The reflecting and absorbing powers, and hence dispersion, of H2SO4 solutions were determined as a function of concentration and of wave-length between 50μ and 150μ. Pure H2SO4 reflects and absorbs the far infrared less than water as is to be expected from the Debye theory on dipole orientation. A broad band around 60μ, similar to the 60μ band in water, was observed in both concentrated and dilute H2SO4. This band appears to be of interatomic origin and possibly a fundamental vibration frequency of the sulphate radical, SO4, due to bending. The reflecting and absorbing powers of H2SO4 solutions are much greater than of pure H2O or H2SO4. This is accounted for by the presence of ions which move in translation to follow the alternations of the electromagnetic waves in the far infrared. The structure of these ions is discussed in reference to other physical properties observed in H2SO4 solutions. It is suggested that in adding less than 5 percent water to H2SO4 possibly ions of SO4-- and OH4++ might be formed; on further dilution, ions of H- and H3SO5 are formed (hydrated HSO4-, with the water making stable six-ring of S–O–H–O–H–O–S); on still further dilution, ions of H+ and SO4-- become most abundant.
Dielectric Constants of Extremely Dilute Solutions
Authors: Hoecker Frank E.
Published: January 2005

The dielectric behavior of unusually dilute solutions of ethyl alcohol in the nonpolar solvents benzol and carbon tetrachloride have been investigated down to 0.00007 molefraction concentration of alcohol. This concentration of molecules corresponds to a gaseous pressure of only 1.5 cm of Hg. The effect of an apparently anomalous behavior often present in the usual method of treating data has been eliminated by a slightly different treatment. Effects of association are entirely absent up to concentrations nearing 0.01. Molecular polarizations of alcohol at 24.5°C, evaluated by least squares from data using the two solvents, agree closely; they also agree well with accepted vapor data. Taking over the molecular refraction of alcohol from optical data, the electric moment of the ethyl alcohol molecule is found to be (1.700±0.006)×10—18 from benzol solution and (1.674±0.005)×10—18 from carbon tetrachloride solution. These are felt to be unusually reliable for solution values; they compare favorably indeed with the two best vapor values, 1.696×10—18 by Miles and 1.686×10—18 by Knowles. Accurate density-concentration relationships for very dilute alcoholic solutions are given.
The Reactions of Deuterium Atoms with Methane and Ethane
Authors: Steacie E. W. R. , Phillips N. W. F.
Published: January 2005

The reactions of deuterium atoms with methane and ethane have been investigated, the atoms being produced by the discharge tube method and by photosensitization with mercury. The activation energies found were 11.7 Kcal. for methane, and 6.3 Kcal. for ethane.

The mechanism of the latter reaction is discussed, and it is concluded that the measured activation energy is that of the reactionD+C2H6=C2H5+HD.Hence the reactionH+C2H6=C2H5+H2must have approximately the same energy of activation. On this assumption the free radical chain theory of first order reactions is discussed in the light of the recent work of Patat and Sachsse.
The Theoretical Treatment of Chemical Reactions Produced by Ionization Processes Part I. The Ortho-Para Hydrogen Conversion by Alpha-Particles
Authors: Eyring Henry , Hirschfelder J. O. , Taylor Hugh S.
Published: January 2005

The possible individual processes that may occur in a gaseous system under irradiation from alpha-particles have been examined from the theoretical standpoint. The ionization, clustering and the fate of the ions have been studied. The ortho-para hydrogen conversion under the influence of alpha-particles has been chosen as an example with which to illustrate the method of treatment. Recent experimental data by Capron have been analyzed to confirm his conclusion that atomic hydrogen is responsible for the large ratio of molecules converted to ions produced (M/N = (700 to 1000)/1). It is also shown that clustering is unimportant in this case and that the paramagnetism of the ions is of negligible importance in producing the spin-isomerization. The role of mercury atoms in removing atomic hydrogen from the system is found to be negligible. Removal of atoms by three body collision of two atoms with molecular hydrogen is slow compared with removal at the walls of the reaction vessel. Analysis of this latter process shows excellent agreement with the experimental data on the conversion efficiency of the system.
The Electron Affinity of Bromine Atoms from Space-Charge Effects
Authors: Glockler Geo. , Calvin Melvin
Published: January 2005

The electron affinity of bromine atoms has been determined from the space-charge effects of a hot tungsten filament in bromine vapor and is found to be 88±3.4 kilocalories.
The Limiting High Temperature Rotational Partition Function of Nonrigid Molecules VI. The Methanol Equilibrium
Authors: Kassel Louis S.
Published: January 2005

The entropy of methanol and the equilibrium constant for methanol synthesis are calculated for two molecular models, one of which rotates freely about the CO bond, while the other possesses a torsional oscillation of frequency 700 cm—1 about that bond. The latter model is indicated by spectroscopic evidence and gives an entropy in close agreement with the third law value and an equilibrium constant close to the mean of the widely scattered experimental results. The former model is supported strongly by valence theory; it can be made to agree with the third law entropy by assuming a zero-point entropy of R log 3, and its rather poor agreement with experimental equilibrium data is not conclusive evidence against it. The true equilibrium constant probably lies between these two calculated values, or at worst slightly beyond one of them.
Kinetics of Recombination of Iodine Atoms
Authors: Rabinowitch E. , Wood W. C.
Published: January 2005

(1) The equilibrium I2+hv→I+I; I+I→I2 was studied in presence of different foreign gases by means of a sensitive optical arrangement. (2) The equilibrium is a ``heterogeneous'' one at low pressure, the atoms recombining mainly by diffusing to the walls. In this region, the dissociation increases with rising pressure. (3) At higher pressure (about 250 mm in He, 40 mm in CO2, etc.), the recombination becomes homogeneous. The transition is a sharp one, and practically no influence of the walls is observed at pressures above the transition point. (4) In the region of homogeneous recombination, the dissociation is exactly proportional to the square root of light intensity and to the inverse square root of pressure, in accordance with the theoretical formulae for the ``recombination by three-body collisions,'' I+I+X→I2+X. (5) The velocity constants of these reactions are calculated for different gases X. The values are given in Table IV. The order of increasing efficiency in promoting recombination is He, A, H2, N2, O2, CH4, CO2, C6H6. One double collision I+I in 530 is a recombining one in helium, and one in 50 in carbon dioxide at atmospheric pressure. (6) The efficiency as third body is higher for the di- and polyatomic molecules than for the monoatomic ones, and increases with growing molecular size and the intensity of the molecular fields of the colliding particles.
The Effect of Rotational Distortion on the Thermodynamic Properties of Water and Other Polyatomic Molecules
Authors: Wilson E. Bright
Published: January 2005

The classical mechanical expression for the energy of a non-vibrating, rotating polyatomic molecule is obtained which includes a correction term arising from the centrifugal distortion of the molecule caused by the rotation. Since the rotational partition function closely approaches the classical phase integral for room temperatures or higher, the latter is used to calculate the effect of centrifugal distortion on the entropy, heat capacity and free energy. The correction terms —ρRT2, 2ρRT and 2ρRT must be added to F, S and Cv, respectively. ρ is a constant characteristic of each molecule. The values of ρ calculated are: H2O, 2.04 10—5; H2S, 1.62 10—5; NH3, 1.45 10—5; CH4, 1.72 10—5; C2H4, 0.79 × 10—5. For water this correction amounts to approximately ½ percent of the heat capacity at the boiling point, or +0.032 entropy unit.
The Crystal Structure of Germanium Disulphide
Authors: Zachariasen W. H.
Published: January 2005

Crystals of GeS2 are orthorhombic. The unit cell contains 24 molecules and has dimensions: a=11.66A, b=22.34A, c=6.86A. Accuracy ½ percent. The space groups is Fdd (C2v19). Eight of the germanium atoms are situated on the twofold axes; all other atoms occupy general positions. The twelve parameters involved have been determined. Every germanium atom is tetrahedrally linked to four sulphur atoms, with an interatomic distance of 2.19A. The angle between the two sulphur bonds is 103°. A three-dimensional network somewhat similar to the silica networks is formed.
The Absorption Spectrum of Diacetylene in the Near Ultraviolet. II
Authors: Woo Sho-Chow , Chu T. C.
Published: January 2005

The absorption spectrum of diacetylene has been reinvestigated with an instrument of higher dispersion. The bands in the region λλ2970–2650A are sharp and narrow, and very closely spaced. Two progressions with a frequency difference ∼690 cm—1 have been found. Those below λ2650A are very diffuse, but with a comparatively simpler gross structure. Ten progressions all with a frequency difference ∼2100 cm—1 have been found. Through a brief and qualitative discussion of the normal vibrations and symmetry properties of the molecule, the frequency differences ∼2100 cm—1 and ∼1900 cm—1 are respectively ascribed as the totally symmetrical v′c≡c(s) and unsymmetrical v′c≡c(a) longitudinal frequencies in the excited state. The frequency ∼635 cm—1 is assigned as one of the fundamental frequencies in the normal state, since bands with this frequency difference were relatively intensified at higher temperatures.
The Effect of Concentration on the Production of the Latent Photographic Image by Hydrogen Peroxide
Authors: Jones Merton W. , Blair Julian M.
Published: January 2005

Much of the density previously reported as produced by short immersions of photographic plates in aqueous solutions of hydrogen peroxide was found to have been produced during the washing interval between exposure and development. Data are presented concerning the production of the latent image by various concentrations of hydrogen peroxide. Analysis of this data suggests that, initially, the net reaction is of the second order. An optimum concentration for the production of maximum density was indicated.
Spectroscopic Studies of the Hydrogen Bond. II. The Shift of the O–H Vibrational Frequency in the Formation of the Hydrogen Bond
Authors: Badger Richard M. , Bauer Simon H.
Published: January 2005

The association spectra of a number of acids and alcohols in the region λλ9000–11,000 have been observed both in solution and in the pure liquids. In each case a broad band with maximum near λ10,000 was observed while in the alcohols an additional weaker band near λ9000 appears to be present. Evidence is presented that the λ10,000 band is to be identified with the O–H group. This evidence includes the behavior of the association band with change in concentration and temperature and its presence in several substances in which absorption other than that due to the O–H group is practically absent in the region studied. New evidence is given that a weak intermolecular hydrogen bond is formed between acetone and methyl alcohol. It is pointed out that the presence of absorption in the narrow O–H bands is not to be taken as evidence of the absence of hydrogen bonds in case the absorption is weak. The character of the O–H absorption in the case of intermolecular hydrogen bonds is discussed and the probable nature of the spectrum in the case of an intramolecular bond is indicated. A relation between the energy of the hydrogen bond and the shift of the O–H vibrational frequency is pointed out and its use is suggested in the interpretation of certain spectra.
The O–H Band in the Vapors of Some Organic Acids and of Tertiary Amyl Alcohol in the Region λ9700
Authors: Bauer Simon H. , Badger Richard M.
Published: January 2005

Absorption bands corresponding to the third harmonic of the O–H vibration have been observed in the vapors of formic, acetic, propionic and trichloracetic acids, with centers at about 10202.8, 10242, 10235 and 10250 cm-1, respectively. Formic acid alone gave a band with resolvable fine structure, but this has unusual features and may be described as a hybrid. The simultaneous presence of characteristics similar to those of both ``perpendicular'' and ``parallel'' type bands of symmetrical molecules is due to the fact that the change in electric moment produced by the O–H vibration has components along two of the principal axes of the molecule. Rotational constants for the formic acid molecule have been evaluated and the moments of inertia were found to be 85.2, 74.4 and 10.81×10-40 g cm2. The structures of the organic acid molecules are discussed and a comparison is made with nitric acid. In tert-amyl alcohol a band with single broad maximum at about 10414 cm-1 was found.
Concentration of N15 by Chemical Methods
Authors: Urey H. C. , Huffman J. R. , Thode H. G. , Fox M.
Published: January 2005

A study has been made on the application of chemical exchange reactions to the problem of the concentration of the nitrogen isotope of atomic weight 15. We have investigated the exchange reactions involving ammonia as the gas phase and solutions of ammonia in water and alcohol, and of ammonium nitrate and ammonium sulfate in water as the liquid phase. The apparatus used consists of an efficient type of fractionation column previously described. It is found that the exchange reaction between ammonium nitrate solution and ammonia is probably the best of all of these for this purpose, except that ammonium nitrate solutions corrode our steel column so badly that their use is impractical in the present apparatus. The exchange between ammonium sulfate solutions and ammonia gas is shown to be more satisfactory for the purpose than any of the other combinations, and has been used to secure a 6½-fold increased concentration of N15. Substantial amounts of nitrogen containing high concentrations of N15 have been produced and these together with the efficient mass-spectrometer method of analysis make possible a wide variety of studies.
Spectral Sensitivity and Light Absorption of Dye-Sensitized Photographic Emulsions
Authors: Leermakers J. A. , Carroll B. H. , Staud C. J.
Published: January 2005

Direct measurements on emulsions sensitized with certain cyanine dyes show a correspondence between the shapes of the light absorption and sensitivity curves in the region of color sensitizing. It was found that the absorption curves of silver bromide dyed with some cyanine dyes are essentially the same as the absorption curves of the dyes in saturated inorganic salt solutions. It is postulated that there are two types of adsorption of cyanine dyes to silver bromide, aggregated and molecular. An emulsion sensitized with a cyanine dye under proper conditions can show sensitivity in different spectral regions, corresponding to the light absorption characteristics of dye adsorbed in the aggregated and molecular states.
The Diffusion of Hydrogen Through Carbonyl Iron at Temperatures from 800° to 1100° Centigrade
Authors: Post C. B. , Ham W. R.
Published: January 2005

The diffusion of hydrogen through hydrogen-purified carbonyl iron shows breaks in the log (rate) vs. 1/T curve at 834, 909 (body-centered→face-centered phase change), 945, 1009, 1056, 1082 and 1103 deg. centigrade. These are average values for three samples of ``Mehl'' iron. The log (rate) vs. 1/T curves at these temperatures are composed of arcs, the above points being ends of these arcs. These points fall on a line whose slope is 4085 deg. Kelvin. Thus b in the expression exp (—b/RT) is given as 18,680 cal./g atom for these points. The above temperatures belonging to the ends of the arcs can be fitted to a Balmer type formula, i.e., T (°K) = C(1/32—1/n2), where n = 6, 7, 8, ..., and C = 13,430±30 for the breaks starting with n = 7, while C = 13,301 for the break with n = 6. This difference is presumably caused by the n = 6 break being in the body-centered phase, while all breaks starting with n = 7 are in the face-centered phase.
An Experimental Determination of Ultrasonic Velocity in Several Gases at Pressures Between One and One Hundred Atmospheres
Authors: Hodge Alfred H.
Published: January 2005

An acoustic interferometer of the resonator or driven type has been developed for the study of the behavior of ultrasonic waves in gases under pressures ranging from vacuum to several hundred atmospheres; measurements of acoustic velocity at several frequencies and in several gases at pressures ranging from one to 100 atmospheres have been made. Increase of velocity with pressure was found for air, N2, He, and H2, a decrease for CO2, the approximate pressure and velocity ranges being respectively as follows: air, 1–101 atmos., 347–371 m/sec.; N2, 1–102 atmos., 353–380 m/sec.; CO2, 1–63 atmos., 270–198 m/sec. The He and H2 were known to be impure. For them an increase in velocity nearly linear with pressure was found. Using frequencies from 88 to 499 kc dispersion was found for CO2 at atmospheric pressure, but almost entirely disappeared above 8 atmospheres. The availability of this method for the indirect determination of specific heats is shown.
The Infrared Absorption by Hydrogen Sulfide
Authors: Sprague Austin D. , Nielsen Harald H.
Published: January 2005

Two of the bands in the spectrum of H2S identified as v3 and v2 have been remeasured under high dispersion. The center of the band identified as v3 is found to be 2685 cm—1 and is a type of band showing no single Q branch at the center and is therefore ascribed to an oscillation of the electric movement along the axis of the intermediate moment of inertia. The fundamental v2 has been remeasured with two different gratings of different resolving power. It has been found to be of the type displaying a broad and partially resolved Q branch at the center and is henceforth identified with an oscillation of the electric moment along the axis of smallest moment of inertia. An estimate of the values of the moments of inertia has been made and these are found to agree well with those given by Cross, but the data here presented is interpreted as evidence for a model where the vertex angle is 85° rather than 92° as given by Cross.
The New Absorption System of Cyanogen Gas in the Near Ultraviolet. System I
Authors: Woo Sho-Chow , Liu Ta-Kong
Published: January 2005

A new system of absorption bands has been found in the region λλ3020–2400 with an absorbing path of three meters and a pressure of two atmospheres. The gross structure of the system is comparatively simple. Two main progressions of bands with frequency differences 2050 cm—1 and 895 cm—1 have been found. The bands in these progressions can be accurately represented by a general formula: ν=A+ω1′v1′+x11′v1′2+ω2′v2′+x22′v2′2+x12′v1′v2′with A = 33,293.63, ω1′+x1′ = 895.75, ω2′ = 2065.38, x22′ = — 15.13 and x12′ = — 8.00. The electronic excitation is mainly at the C – N bond. The structure of the molecule in the excited state, its normal frequencies and symmetry properties are also discussed. The frequency difference 2050 cm—1 is considered as due to the totally symmetric longitudinal (C – N) vibration in the excited, state and a tentative assignment is suggested as follows: ν1′ = 895 cm—1, ν2′ = 2050 cm—1, ν3′ = 1770 cm—1, δ2′(u) = 210 cm—1. Other possible assignment has also been briefly discussed.
The Dissociation Pressure of a Solid Under Inert Gas Pressure
Authors: Perkins Alfred J.
Published: January 2005

The mole fraction of ammonia in equilibrium with barium chloride octammine at 32°C and at various pressures of helium, argon and nitrogen has been determined. At every pressure, the mole fraction is greater than that expected by a simple application of the Poynting relation. An equation has been derived for the chemical potential of a component of a gaseous mixture in terms of the total pressure, the mole fraction, and the second virial coefficients. This equation has been tested and shown to give fair agreement between calculated and observed values. One advantage is the fact that it can be used to calculate the mole fraction of the component of a gas mixture which arises from the dissociation of a solid with which the mixture is in equilibrium. It is also shown how these measurements might be used to calculate the second virial coefficients of gaseous mixtures.
The Thermal Decomposition of Ethane Remarks About a Paper by E. W. R. Steacie and N. W. F. Phillips
Authors: Sachsse Hans
Published: January 2005

On account of the experimental value of the reaction D+C2H6 according to Steacie and Phillips the radical chain mechanism in the decomposition of ethane by F. O. Rice is anew discussed. It results that even now this theory does not agree with the experiment.
Vibration Spectra and Molecular Structure II. The Force Constants of the C–C and C–O Bonds in Organic Molecules
Authors: Bonner Lyman G.
Published: January 2005

Force constants are calculated from known vibration frequencies for several of the simpler organic molecules by an approximate method involving neglect of the interactions between motions of hydrogen atoms and other atoms. Frequency expressions are given for several special forms of the triatomic molecule, and the C–C and C–O force constants are calculated for ethane, propane, cyclopropane, ethylene oxide, ethyl alcohol, isobutane, dimethyl ether, and methyl alcohol. The values obtained are, in general, in the neighborhood of 3.8 and 4.5×105 dynes/cm, respectively.
The Double Minimum Problem Applied to the Ammonia Molecules
Authors: Wall F. T. , Glockler George
Published: January 2005

A simple quantum-mechanical calculation has been made to obtain the doublet separations for the parallel type frequencies of the ammonias. The calculated values for the separations are: NH2D (21), NHD2 (11) and ND3 (5.8) cm—1, which compare favorably with observed values: NH2D (20), NHD2 (10) and ND3 (3.4) cm—1.
The Influence of Dipole-Dipole Coupling on the Specific Heat and Susceptibility of a Paramagnetic Salt
Authors: Van Vleck J. H.
Published: January 2005

The mutual magnetic potential energy of atomic magnetic dipoles is unimportant in salts of high dilution at ordinary temperatures, but becomes important in determining the temperature scale in the new very low region obtained by magnetic cooling. This ``dipole-dipole'' energy is not to be confused with exchange interaction which is important in concentrated magnetic materials and which is there responsible for ferromagnetism at ordinary temperatures. The partition function, and hence the entropy, specific heat, and susceptibility are calculated for a paramagnetic solid inclusive of dipole and simultaneously also feeble exchange coupling. In Sections 3–4 the computation is made for atoms otherwise free, but in Section 6 they are subjected in addition to a crystalline Stark field. Comparison with experiment is made in the following paper by Hebb and Purcell. Our method of partition functions is to be contrasted with the usual, essentially static Lorentz method of representing dipole-dipole coupling by a local field, e.g., H+4πM/3 for a long test body. The Lorentz procedure is shown to be only a first approximation, which is really warranted if the density is so low or the temperature so high that one may neglect all terms but the first in the development of the partition function in 1/T. Otherwise the usual results of the local field method are obtained only by an extrapolation which is comparable with the assumption in Heisenberg's theory of ferromagnetism of identical energy for all states with the same crystalline spin. Two other types of extrapolation, based on a second approximation, are obtained which correspond respectively to assuming a Gaussian distribution of energies for these states and to use of the local field proposed by Onsager. The latter seems to be much the more satisfactory of the two.
The Entropies of n-Butane and Isobutane, with Some Heat Capacity Data for Isobutane
Authors: Parks George S. , Shomate C. Howard , Kennedy W. D. , Crawford Bryce L.
Published: January 2005

The entropies of n-butane (S298° = 75.8 e.u.) and isobutane (S298° = 70.0 e.u.) have been calculated from thermal data by the third law of thermodynamics. In this connection, heat capacity data for isobutane over the temperature range 79°—261°K have been obtained by the Nernst method and also, as a partial basis for these calculations, the mode of extrapolating entropies below liquid air temperatures has been critically examined. The discrepancies between these new results and the corresponding entropies obtained by statistical methods appear too large to be accounted for by errors in the thermal data or extrapolations involved. The thermodynamics of the isomerization reaction is briefly considered.
Theory of Surface Tension of Aqueous Solutions of Dipolar Ions
Authors: Ariyama Kyozo
Published: January 2005

A theory of surface tension of solutions of the dipolar ions is proposed. The theory is based on the idea of ``image force'' at the boundary of air and water. The experimental facts are satisfactorily accounted for by the theory.
Raman Spectra of Amino Acids and Related Compounds IV. Ionization of Di- and Tricarboxylic Acids
Authors: Edsall John T.
Published: January 2005

A systematic study of Raman spectra has been made for a large number of carboxylic acids and their salts dissolved in water. In particular, malonic acid and its two sodium salts, and malonic-d2 acid-d2 and its disodium salt, have been studied in detail. The substitution of deuterium in this molecule permits the vibrations arising primarily from the — CH2 group to be distinguished from those arising primarily from the carboxyl groups. The Raman spectrum of deuterium oxide has been redetermined in connection with these studies. The following general conclusions have been reached: (1) The powerful ``carbonyl'' frequency near 1700 cm—1 is always found when an un-ionized carboxyl group is present, and always vanishes on ionization of the carboxyl. (2) One or more intense Raman lines near 1400 cm—1 can always be found in a substance containing an ionized carboxyl group. Such lines are definitely polarized, and presumably correspond to a symmetrical valence oscillation of the COO— group. Like the ``C=O'' frequency near 1700, these lines are almost unaffected by deuterium substitution. Deformation frequencies arising from —CH2 or —CH3 groups commonly lie in the same range; the marked effect of deuterium substitution, however, clearly differentiates these from the vibrations of the —COO— group. (3) Other Raman lines, near 1330 and 1580 cm—1, are frequently but not invariably found in substances containing ionized carboxyl groups. (4) Most of the substances studied show strong Raman lines between 700 and 950 cm—1, which increase in frequency by 30 to 50 cm—1 on ionization. These lines are strongly polarized, and in malonic acid are noticeably depressed in frequency by deuterium substitution. (5) Certain frequencies below 600 cm—1 are virtually unaffected either by ionization or by deuterium substitution. These presumably represent bending or twisting vibrations of the heavy molecular framework. The ``C=C'' frequency near 1650 in crotonic and maleic acids is unchanged by the ionization of a neighboring carboxyl group. The Raman spectra of d-tartaric acid and of mesotartaric acid, although very similar, show definite differences which are well beyond the experimental error. The structure of the ionized carboxyl group is undoubtedly closely related to that of the nitro group. Both show intense polarized Raman lines near 1400, probably corresponding to the same type of oscillation in both cases; and the bond strength in the two groups is probably nearly the same.
The Determination of the Constants of Harmonic Vibrations
Authors: Redlich Otto , Tompa Hans
Published: January 2005

A general method is developed to find the relations between constants of the potential energy and the frequencies of point systems for harmonic vibrations. Useful formulas are derived (Eqs. (16) and (23)); and matrices required frequently for the solution of problems are tabulated. Relations are also found between the force constants of a molecule with a number of equivalent atoms and the vibration frequencies of an isotopic molecule of a lower degree of symmetry. This also gives the relations between the frequencies of isotopic molecules of different degrees of symmetry.
A Partition Function for Liquid Mercury
Authors: Kincaid John F. , Eyring Henry
Published: January 2005

From a model for liquid mercury we have formulated a partition function of sufficient generality to give by means of the usual statistical mechanical equations the vapor pressure, the equation of state, the entropy of melting and the specific heats. The partition function involves four parameters characterizing the particular substance concerned. Having chosen these parameters for mercury it is possible to calculate all the above properties from the melting point to the boiling point within experimental error except for a slight divergence of about 2 percent (0.1 cal./mole/degree) in the specific heat at the melting point. The van der Waals' constants follow from the theory and when employed in his equation give satisfactory agreement between calculated and observed critical properties. The long liquid range, low melting point, and low viscosity of metals are all in agreement with our model in which it is assumed that in the liquid the kernels move independently of their valence electrons.
The Temperature Variation of Some Thermodynamic Quantities
Authors: Murphy George M.
Published: January 2005

The quantity, (F0—E00)/T, calculated from spectroscopic data has been fitted to a five constant equation in T for 19 molecules. It may be differentiated and integrated to give values of S0, E0, H0 and Cp0 between 298.1 and 3000°K and is sufficiently exact for most purposes. The equilibrium constant for exchange reactions involving isotopes has been calculated and in each case, maxima exist and in one case a minimum also. This effect probably occurs at some temperature for all reactions involving isotopic molecules although not for other equilibria. An optimum temperature therefore exists for separation of isotopes by exchange reactions.
The Lattice Energy of Solid CO2
Authors: Sponer H. , Bruch-Willstätter M.
Published: January 2005

It is possible to account for the measured sublimation heat of solid CO2 by calculating the attraction energy according to London's theory of van der Waals forces; or, when the second approximation of the attractive forces is included, by considering also the electrostatic energy due to the dipole moments and the repulsive energy, the latter being deduced from the equilibrium condition. For the calculation of the electrostatic energy the picture of point charges with definite distances seems preferable to that of short dipoles.
Intensities of Electronic Transitions in Molecular Spectra II. Charge-Transfer Spectra
Authors: Mulliken Robert S.
Published: January 2005

Two related types of high intensity molecular spectra are discussed. These are designated as charge-resonance spectra and charge-transfer spectra. In the molecular orbital approximation, both these types usually involve transfer of one electron from a bonding to the corresponding antibonding molecular orbital. In the atomic orbital approximation, charge-resonance spectra involve a transition from a symmetrical to a corresponding antisymmetrical state, the wave function of each of these two states being a linear combination of two wave functions representing two hypothetical states of a molecule that are equivalent or nearly so but different in charge distribution. Charge-transfer spectra in the atomic orbital approximation involve a transition from a state having a non-ionic to one having an ionic wave function (N→V transition). Theoretical equations for dipole strengths and f values for both these types are given, in each case calculated according to each of the two approximations. The equations are very simple, the dipole strength being proportional to the distance across which the charge resonates or is transferred.

Examples of charge-resonance spectra in H2+, O2+, and NO are cited, and N→V (charge-transfer) transitions in the spectra of the molecules H2, O2, C2H4, C6H6, and the halogens are discussed. Although experimental data are scanty, they appear to be in harmony with the theory. For the O2 Schumann-Runge bands, where f is accurately known experimentally, its value is intermediate between the values calculated theoretically according to the two approximations. A suggestion is made to explain Carr and Stücklen's result of progressive broadening toward longer wave-lengths in the N→V spectrum as radicals are substituted for H atoms in C2H4. The 1A1g→1E1u transition in C6H6 calculated by Sklar and identified by him with bands near and below λ2000 is here concluded to be of the N→V class. In connection with the theory of light absorption in organic compounds, it will be shown in later papers that intense transitions in the visible and ordinary ultraviolet probably can be accounted for in a large proportion of cases (including dyes) as charge-transfer (N→V) spectra, or, in part, as charge-resonance spectra. The existence of spectra of the charge-resonance type in certain kinds of dyes has already been recognized and very briefly discussed by Pauling in the new edition of Gilman's Organic Chemistry.
The Diffusion of Hydrogen Through Oxygen-Free Copper
Authors: Ham W. R.
Published: January 2005

A precise determination has been made of the diffusion of hydrogen through copper that is spectroscopically oxygen-free. The range of temperatures is from 450°C to 1050°C. The copper appears perfectly homogeneous over the entire range, the equation followed being Rate=ApyTze−b/T,where p is pressure, T absolute temperature, A and b constants characteristics of copper. The value of z is about +0.5±0.2 as was found in pure nickel. The principle point to be noted is that y=0.50±0.01 even at 450°C. It is well known that copper containing any appreciable amount of oxygen shows isotherms in this region with a value of y as large as 0.8 in some instances, when log R is plotted against log p. When this same copper diffusor is slightly charged with oxygen the value of y becomes greater than 0.5, except at high temperatures. However, when isotherms are plotted log rate against log pressure, the result is a perfectly straight line in all cases. It now appears that the removal of all traces of oxygen from copper has the same effect on low temperature hydrogen diffusion isotherms as the removal of all carbon from iron and nickel, viz., these isotherms become perfectly normal, the rate varying exactly as the square root of the pressure.
Changes of Phase and Transformations of Higher Order in Monolayers
Authors: Dervichian D. G.
Published: January 2005

The gaseous, liquid, mesomorphous and solid states in monolayers are defined and their close connection with the corresponding states in three dimensions rigorously established. This involves a new treatment of the two-dimensional liquid and of its transformation to the mesomorphous state. The properties of the three-dimensional vitreous state of fatty substances are shown to be particularly important in connection with the behavior of monolayers. The different critical and transformation temperatures are also defined and their significance explained. From this is derived a systematic classification of the different types of isotherms observed. By determining the variations of the compressibility, viscosity and apparent dipole moment with change of area, higher order transformations are detected in monolayers. These transformations occur at the same areas as those at which ordinary phase transformations occur at lower temperatures.
Electrostatic Effects on Ionization Constants
Authors: Baughan E. C.
Published: January 2005

The equation of Born for the self-energy of an ion is applied to the heats of ionization of acids and bases, following a treatment by Gurney. In this way the variations in these heats with temperature are quantitatively explained, and approximate ionic radii predicted. Further applications to the ionization of amino acids and the variation of dissociation constants as between different solvents are discussed.
The Vibrational Spectra of 1,2 Dihalogen Ethanes and the Question of Internal Rotation
Authors: Wu Ta-You
Published: January 2005

On symmetry considerations, it is shown that a satisfactory assignment can be given to all the observed infra-red and Raman frequencies of the 1,2 dihalogen ethanes provided both the cis- and the trans-forms are assumed to exist. The potential functions for the internal rotation in such molecules derived from the temperature variation of the electric moments and from electron diffraction measurements are such, however, as to give a negligibly small number of molecules in the cis-configuration which is unstable. A suggestion is made to account for the apparent difference between the spectroscopic and the other evidences.
The Statistical Mechanics of Condensing Systems VI. The Treatment of a System of Constant Energy
Authors: Streeter S. F. , Mayer Joseph E.
Published: January 2005

The equations for the thermodynamic functions of an imperfect gas up to and including the pressure of condensation, are calculated for a one-component system consisting of chemically saturated molecules. The method starts with the calculation of the phase volume available to a system below a given energy. The thermodynamic functions are expressed in terms of integrals over the configuration space of a few molecules, the integrands involving the mutual potentials. The equations derived are formally equivalent to those derived in the previous papers of this series, using the Gibbs method.
A Differential Method Applied to the Surface Ionization of Sodium Halides on Tungsten
Authors: Johnson A. A. , Phipps T. E.
Published: January 2005

A differential molecular-beam method for the study of the surface ionization of salts was developed. A reference filament and a working filament were placed in the paths of molecular beams emitted from the same furnace orifice; and the ratios of the positive ion currents collected from the two surfaces were measured with a center-tap galvanometer for different temperatures of the working filament. This method was applied to the study of the ionization of sodium halides on tungsten and tungsten-oxygen surfaces. The results were not in close agreement with the simple theory of the ionization of a gaseous sodium atom at a tungsten surface. The energy quantity, (I—Φ)ε, (I being the ionization potential of the alkali atom, and Φ, the work function of the surface) was about 0.3 v.e. less than that demanded by theory. To explain this defect an extension was made of the simple theory, in which it was assumed that a small fraction of the surface was covered with halogen atoms even to high temperatures. The experimental results could then be explained upon the assumption that from two to four percent of the tungsten surface (the exact value depending upon the particular halide and tungsten surface involved) held adsorbed halogen atoms up to 2600°K.
Chain Length and Chain-Ending Processes in Acetaldehyde Decomposition
Authors: Burton Milton , Taylor H. Austin , Davis Thomas W.
Published: January 2005

The C–C bond strength in acetaldehyde is probably less than a previously postulated value of 93 kcal. and may be as low as the 75 kcal. value calculated by Grahame. The chain-ending processes in the pyrolysis, in the azomethane-induced decomposition, and in the photolysis of acetaldehyde are all bimolecular but it is clear that the processes in the second and the third decompositions cannot be identical. The uncertainty of the process in the pyrolysis introduces an uncertainty into Grahame's calculation. In any event, the process is not the combination of methyl radicals in the gas phase to yield ethane. In the photolysis (and perhaps in the pyrolysis) HCO seems to be involved in the chain-ending reaction. In the induced decomposition CH3CO seems to be concerned. The recombination of methyl radicals as a wall reaction may occur in packed vessels. Activation energies of the various reactions are discussed.