The ideas of the first and second papers in this series, which make it possible to interpret entropy data in terms of a physical picture, are applied to binary solutions, and equations are derived relating energy and volume changes when a solution is formed to the entropy change for the process. These equations are tested against data obtained by various authors on mixtures of normal liquids, and on solutions of non-polar gases in normal solvents. Good general agreement is found, and it is concluded that in such solutions the physical picture of molecules moving in a ``normal'' manner in each others' force fields is adequate. As would be expected, permanent gases, when dissolved in normal liquids, loosen the forces on neighboring solvent molecules producing a solvent reaction which increases the partial molal entropy of the solute. Entropies of vaporization from aqueous solutions diverge strikingly from the normal behavior established for non-aqueous solutions. The nature of the deviations found for non-polar solutes in water, together with the large effect of temperature upon them, leads to the idea that the water forms frozen patches or microscopic icebergs around such solute molecules, the extent of the iceberg increasing with the size of the solute molecule. Such icebergs are apparently formed also about the non-polar parts of the molecules of polar substances such as alcohols and amines dissolved in water, in agreement with Butler's observation that the increasing insolubility of large non-polar molecules is an entropy effect. The entropies of hydration of ions are discussed from the same point of view, and the conclusion is reached that ions, to an extent which depends on their sizes and charges, may cause a breaking down of water structure as well as a freezing or saturation of the water nearest them. Various phenomena recorded in the literature are interpreted in these terms. The influence of temperature on certain salting-out coefficients is interpreted in terms of entropy changes. It appears that the salting-out phenomenon is at least partly a structural effect. It is suggested that structural influences modify the distribution of ions in an electrolyte solution, and reasons are given for postulating the existence of a super-lattice structure in solutions of LaCl3 and of EuCl3. An example is given of a possible additional influence of structural factors upon reacting tendencies in aqueous solutions.
A. The basic equations of fluid dynamics and the generalizations and simplifications required for their use in theories of one-dimensional, steady-state, non-viscous flame propagation.
A pure sample of CH3D has been prepared and studied in the mass spectrometer. The mass spectrum of CH3D cannot be predicted from that of CH4 by assuming complete similarity between H and D (except mass). More information has been obtained on the difference in behavior of H and D on electron impact previously noticed by Delfosse and Hipple for C2H2D2. There is a difference in dissociation probability of C–H and C–D bonds which is approximately constant for several ionization processes and over a considerable range in electron energy. In addition to this there is a difference in behavior of H atoms in CH4 and H atoms in CH3D. In order to account for the mass spectrum of CH3D in terms of the mass spectrum of CH4 both these effects must be taken into consideration. Re-examination of the data of Delfosse and Hipple points not only to the difference between H and D atoms in C2H2D2, but also to a difference in behavior of H atoms in C2H4 and H atoms in C2H2D2.
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