THE THERMODYNAMIC PROPERTIES OF HYDROGEN SELENIDE

Abstract

Hydrogen selenide may be generated by the reaction of hydrogen gas with liquid selenium according to the reaction[Formula: see text]where[Formula: see text]The equilibrium constant K of this reaction was measured by passing hydrogen over liquid selenium at controlled rates of flow over the temperature range 525–625 °C. The equilibrium ratio of hydrogen to hydrogen selenide was determined by gas analysis. Over the temperature range 525–625 °C, the equilibrium constant can be expressed by the equation[Formula: see text]This expression leads to ΔH298° = 9 174 ± 107 cal mole−1, ΔF298° = 5 132 cal mole−1, and ΔS298° = 13.56 e.u. (entropy units) for the respective heat, free energy, and entropy of formation of hydrogen selenide from hydrogen and crystalline selenium.