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1 Dec 1934

Volume 2, Issue 12, pp. 825-891


Combination‐Scattering and ``Association of Molecules''

S. I. Leitman and S. A. Ukholin

J. Chem. Phys. 2, 825 (1934); http://dx.doi.org/10.1063/1.1749402 (2 pages) | Cited 2 times

Online Publication Date: 3 November 2004

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The molecular association of polar liquids was studied by the combination‐scattering (Raman‐spectra) method. In the spectra of a water solution of acetic acid the lines corresponding to the wave number 623 cm—1 changed their relative intensity at a change of the concentration of solution. This wave number is therefore characteristic of acetic acid complex molecules. No associative lines were observed in the combination spectra of nitrobenzol solution in CCl4.

Formation of Negative Ions in Gases by Electron Attachment Part I. NH3, CO, NO, HCl and Cl2

Norris E. Bradbury

J. Chem. Phys. 2, 827 (1934); http://dx.doi.org/10.1063/1.1749403 (8 pages) | Cited 36 times

Online Publication Date: 3 November 2004

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With the same method and apparatus employed in the study of negative ion formation in O2 by electron attachment, the results have been extended to all the common diatomic gases and NH3. No negative ions are formed in NH3 below an X/p of 7.5; beyond that point they are formed with increasing probability as the energy of the electrons increases. The phenomenon is interpreted as dissociation of the molecule with the formation of NH— at an electronic energy of approximately 3 volts, the NH3 molecule having itself no electron affinity. No negative ions could be formed in CO at the electronic energies available, and the molecule is presumed to have no electron affinity. Negative ions are formed by electron attachment in NO, the probability increasing with decrease in electronic energy. A linear variation in probability of attachment with pressure is also observed in NO which is due to a collision with a pair of NO molecules held together by weak attractive forces. Negative ions are formed in HCl with a probability which increases with increasing electronic energy suggesting that dissociation of the molecule occurs here as well. Similar results are obtained in Cl2 where it has been known that the energy of the attachment process must be more than sufficient to dissociate the molecule. The experiments indicate several types of attachment processes which can occur in gases and the possibilities of energy dissipation in ion formation. In general the most favored process is the carrying off of the energy by a third body involved in the process.

The Formation of Negative Ions in Gases Part II. CO2, N2O, SO2, H2S and H2O

Norris E. Bradbury and Howard E. Tatel

J. Chem. Phys. 2, 835 (1934); http://dx.doi.org/10.1063/1.1749404 (5 pages) | Cited 36 times

Online Publication Date: 3 November 2004

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The study of electron attachment has been extended to the gases CO2, N2O, SO2, H2S and H2O. No negative ions were observed in CO2. In N2O, below X/p=2, no negative ions were formed, and the N2O molecule apparently has no electron affinity. For values of X/p>2, the electrons possessed sufficient energy to dissociate the molecule and negative ions, probably O—, were formed in increasing numbers. SO2 showed an electron affinity forming negative ions with electrons of very low velocity. The probability of attachment decreased as X/p increased until an X/p of about 13 when an increase in probability of formation was noted. This is probably due to dissociation and formation of SO—. No negative ions were observed in H2S below an X/p of 6. For greater values of X/p negative ions were formed in increasing amounts presumably by a dissociation process with the formation of HS—. A similar behavior was observed in H2O at an X/p=10, with the formation of OH—. Negative ion formation in H2O was also observed at low X/p and varied with the pressure of the gas. This is explained as being due to negative ion formation from small molecular aggregates existing near the point of condensation of the water.

Note The Electronic Configuration of Molecules and Their Electron Affinity

Norris E. Bradbury

J. Chem. Phys. 2, 840 (1934); http://dx.doi.org/10.1063/1.1749405 (1 page) | Cited 3 times

Online Publication Date: 3 November 2004

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X‐Ray Studies of the Molecular Arrangement in Liquids

S. Katzoff

J. Chem. Phys. 2, 841 (1934); http://dx.doi.org/10.1063/1.1749406 (11 pages) | Cited 57 times

Online Publication Date: 3 November 2004

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An improved technique has been developed for taking x‐ray diffraction photographs of weakly absorbing liquids. Photographs of water, heptane, decane, benzene and cyclohexane have been taken and several hitherto unobserved details have been discovered. The photographs of water have been mathematically investigated by the method of Zernike and Prins, and it was concluded that nearly every molecule has four others around it. No evidence was found either for the definite ``quartz‐like'' arrangement or for the extensive degree of close packing which are postulated by Bernal and Fowler. With the organic compounds there was apparent in every case a striking resemblance of the outer parts of the photographs to electron diffraction photographs of the corresponding vapors. This is in agreement with Debye's prediction and argues for a relatively low degree of periodicity in the liquid structure. It has been shown further that the two outer bands which occur in the photographs of the normal hydrocarbons should appear whenever the molecules of the liquid consist largely of lengths of straight saturated hydrocarbon chain. Some discussion of the structure of the organic liquids has been given. In particular, a theory on the structure of liquid benzene has been postulated and found, using the method of Zernike and Prins, to predict with satisfactory accuracy the observed photograph. The viewpoint which has been found useful in the present discussions is that, to a predominating extent, adjacent molecules in the liquid are held together in very nearly the same manner as in the crystal, while, except for this, the arrangement is random.

The Ultraviolet Absorption of Methane

A. B. F. Duncan and John P. Howe

J. Chem. Phys. 2, 851 (1934); http://dx.doi.org/10.1063/1.1749407 (2 pages) | Cited 14 times

Online Publication Date: 3 November 2004

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The absorption spectrum of methane from 1450A to 850A is found to be entirely continuous and all excited states up to the first ionization potential are repulsive.

Entropy and the Absolute Rate of Chemical Reactions I. The Steric Factor of Bimolecular Associations

O. K. Rice and Harold Gershinowitz

J. Chem. Phys. 2, 853 (1934); http://dx.doi.org/10.1063/1.1749408 (9 pages) | Cited 17 times

Online Publication Date: 3 November 2004

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The equilibrium constant for a bimolecular association may be expressed in terms of the energy change, ΔE, and standard entropy change, ΔS°, on association. On account of the well‐known relation between the equilibrium constant, and the rate constants of the bimolecular association and its reverse, the corresponding unimolecular decomposition, the values of these rate constants could be determined separately, if one could divide each of the terms, ΔE and ΔS°, into two parts, in the proper way. The proper method of dividing ΔE is known; this paper is concerned with the division of ΔS°. Considered from a statistical point of view, the entropy of a system depends upon the volume in phase space available to the system under fixed thermodynamic conditions. The separate rate constants will depend upon the fraction of the phase space in which it is possible for the reaction under consideration to take place. Application of this principle leads to an interpretation of the collision number and the steric factor of bimolecular association reactions. The known bimolecular associations have been discussed from this point of view.

The Theory of the Glass Electrode. III Statistical Explanation of the Alkaline Solution Behavior

Malcolm Dole

J. Chem. Phys. 2, 862 (1934); http://dx.doi.org/10.1063/1.1749409 (5 pages) | Cited 7 times

Online Publication Date: 3 November 2004

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The application of Gurney's quantum and statistical mechanical theory of electrochemistry to the glass electrode results in an equation for the alkaline solution behavior identical with one previously obtained by the author except that the constants of the equation have a more reasonable significance. A qualitative explanation of the inability of negative ions to affect the glass electrode potentials is also given.

A Study of the Methods of Interpretation of Electron‐Diffraction Photographs of Gas Molecules, with Results for Benzene and Carbon Tetrachloride

Linus Pauling and L. O. Brockway

J. Chem. Phys. 2, 867 (1934); http://dx.doi.org/10.1063/1.1749410 (15 pages) | Cited 36 times

Online Publication Date: 3 November 2004

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The reliability and accuracy of the visual method of interpreting electron‐diffraction photographs, consisting in the correlation of values of (4π sin ν / 2) / λ obtained by visual measurement of rings of apparent maximum and minimum intensity with x values from a simplified theoretical curve (Eq. (7) or (8)), have been tested in the following ways: (a) The measurement and interpretation of ``artificial electron‐diffraction photographs'' of bromine; (b) the comparison of electron‐diffraction and bandspectral values of interatomic distances for bromine, chlorine and iodine chloride; (c) the study of microphotometer records for benzene, and comparison of results with those of the visual method; (d) the study of micro photometer records for carbon tetrachloride, and comparison with the visual method. It is concluded that the visual method when carefully applied leads to values of interatomic distances accurate to about 1 percent (probable error), or to ☒ percent in favorable cases. The regular plane hexagon model of the benzene molecule is verified, the carbon‐carbon distance in the ring being determined as 1.390±0.005A. The carbon‐chlorine distance in the carbon tetrachloride molecule is determined as 1.760±0.005A. A brief discussion of the methods and results of other investigators is given.

Raman Effect of Acetylenes. I. Methyl‐, Dimethyl‐ and Vinyl‐Acetylene

George Glockler and H. M. Davis

J. Chem. Phys. 2, 881 (1934); http://dx.doi.org/10.1063/1.1749411 (9 pages) | Cited 20 times

Online Publication Date: 3 November 2004

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An improved helical discharge tube containing neon and mercury with a saturated solution of sodium nitrite as filter served as a monochromatic source of radiation (4358 Hg). A mechanical filter avoided overexposure of the exciting radiation. The vibration frequencies were studied on the basis of the symmetry properties of the molecules and the usual assignments have been made. Faint rotation lines were found accompanying the C ⋮ C vibration in liquid dimethyl‐acetylene. They are interpreted as rotation of the six hydrogen atoms around the figure axis of the molecule. The moment of inertia is I = 10—39 g×cm2. The three compounds were studied in the liquid state.
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Note on ``The Experimental Determination of the Heat Capacity of Explosive Gases.'' A Correction

Bernard Lewis and Guenther von Elbe

J. Chem. Phys. 2, 890 (1934); http://dx.doi.org/10.1063/1.1749412 (1 page) | Cited 1 time

Online Publication Date: 3 November 2004

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Abstract Unavailable

The Raman Spectrum of Fluorobenzene

John W. Murray and Donald H. Andrews

J. Chem. Phys. 2, 890 (1934); http://dx.doi.org/10.1063/1.1749413 (1 page) | Cited 1 time

Online Publication Date: 3 November 2004

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The Influence of D2O and HDO on the Mutarotation of Glucose

W. H. Hammill and Victor K. La Mer

J. Chem. Phys. 2, 891 (1934); http://dx.doi.org/10.1063/1.1749414 (1 page) | Cited 3 times

Online Publication Date: 3 November 2004

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Abstract Unavailable
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