The Temperature Variation of Some Thermodynamic Quantities

Abstract

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.