Volume 12, Issue 9, 01 September 1944
Index of content:
12(1944); http://dx.doi.org/10.1063/1.1723957View Description Hide Description
The energy of dissociation of H2O into H+OH was measured by an experiment developed from the method of Bonhoeffer and Reichardt. A spectrograph of high resolving power served for the measurement of the intensity of the absorptionspectrum of OH in a heated mixture of water vapor and oxygen. The result (for 0°K) was H+OH→H2O−118.2±0.7 kcal. and O+H→OH−100.1±0.9 kcal. The probabilities of transition of the lines of the OH band were recomputed.
12(1944); http://dx.doi.org/10.1063/1.1723958View Description Hide Description
Vapor pressures of crystalline KCl, KBr, KI, and NaCl have been measured in the pressure range of 10−1 to 10−7 mm by a surface ionization method. Heats and entropies of vaporization are calculated from the data. The heats of vaporization at 0°K and entropies at 298°K are also calculated. From the data, saturated KCl vapor is shown to be less than 2 percent associated at 800°K and the heat of dissociation of (KCl)2 is shown to be less than 47 kcal.
12(1944); http://dx.doi.org/10.1063/1.1723959View Description Hide Description
An investigation has been made of the reaction between hydrogen atoms and acetylene. With the large hydrogen atom concentrations produced in the discharge tube, catalytic recombination of hydrogen atoms occurs but no hydrogenated products could be detected. With small hydrogen atom concentrations resulting from mercury photosensitization, ethane and butane are produced together with a partially hydrogenated polymer. The results are discussed from the point of view of the elementary reactions involved and it is concluded that ethyl and vinyl radicals play an important part in the reaction.
12(1944); http://dx.doi.org/10.1063/1.1723960View Description Hide Description
The kinetic theory of rubberelasticity is extended in two respects. First, the distribution of relative displacements of every chain atom is considered, not merely the distribution of relative chain‐end displacements. Second, the rate of approach to elastic equilibrium, as well as the equilibrium itself, is considered. As a first approximation, it is predicted that a linear amorphous polymer will possess a distribution of elastic retardation times of the form J(τ)dτ=(C ln τ — D)d ln τ, where C and D are constants characteristic of the material.
12(1944); http://dx.doi.org/10.1063/1.1723961View Description Hide Description
In continuation of Part I and Part II of this paper, bond moments are calculated for such molecules as are formed by a marked central atom in a higher state of valency. Again the classical structures are taken as a basis. The bond moments are additive in the same molecule and unchanged from molecule to molecule as long as the multiplicity of the bond and the state of valency of either atom remain the same. This treatment on the basis of classical formulae makes possible the simple and straightforward calculation of the total moments of a considerable number of molecules formed by pentavalent nitrogen (azoxybenzenes, N‐ethers of nitrobenzophenoneoximes), for which no other such calculation has been possible so far. Observable facts of dipole measurements, therefore, are at least as well represented by the classical structures and their underlying concepts, as by any other theory of the covalent bond. Hence, dipole moments do not provide any evidence of the existence of such linkages as a semipolar double bond or its wave‐mechanical equivalent, i.e., enhanced resonance with ionic parent structures.
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