G. M. Murphy

The Free Energy of Iodine and Hydrogen Iodide from Spectroscopic Data

Partition functions have been calculated for HI, I2 and I atom between 298.1 and 1500°K from spectroscopic data and the results have been fitted to a free energy equation of the usual thermodynamic form which may be differentiated and integrated to give change of heat content, specific heat and entropy for chemical reactions involving HI, I2, I and H2. The experimentally determined equilibrium constants for the reactions I2→2I and HI→½H2 +½I2 have been compared with the theoretical equilibrium constants. For the latter reaction, it is shown that the results of Bodenstein may be in error due to incorrect temperatures. Reliable values have been given for the heat of dissociation of iodine and hydrogen iodide at 25°C.

The Use of the Interferometer in the Isotopic Analysis of Water

A method of analysis of mixtures of protium and deuterium oxides is presented. It consists in calibrating the apparent difference in indices of refraction of natural water and that containing higher concentrations of deuterium oxide, as obtained by a Zeiss water interferometer, against the corresponding differences in specific gravities. It is found that these two quantities are not proportional. The precision of measurement in the neighborhood of an experimentally determined specific gravity in a 40.06 mm cell is 0.01 percent.

The Rate of Thermal Decomposition of Deuterium Iodide

The partition functions for deuterium iodide have been calculated at temperatures from 300 to 1500°K. Constants were calculated for an equation to give the value of the free energy function at any temperature within this range. A similar calculation was made for D2 using the data of Johnston and Long. Combining these with the data for the other molecules involved, the equilibrium constant for the decomposition of deuterium iodide and for the exchange reaction was calculated. These results can be differentiated and integrated to give values for ΔH0, ΔCp and ΔS0. The equilibrium constant for the reaction H2+2DI⇄D2+2HI has been plotted against the temperature from 300 to 1500°K. The equilibrium constant for the reaction DI ⇄½D2+½I2 has been calculated. The rate of thermal decomposition of deuterium iodide was measured between 660 and 719°K. The experimental ratio of the rate constants for the reactions HI→½H2+½I2 and DI→½D2+½I2 has been compared with the theoretical value of Wheeler, Topley and Eyring. Contr...