Thermodynamic analysis of metal oxides, metal peroxides and metal hydrides

Abstract

The standard entropy differences between metal oxides (metal peroxides) and metal elements Δ S were roughly expressed by the following equation, |Δ S | ∝ Rln|Δ V |, R: gas constant, Δ V : volume differences below 10 cm 3 /molO 2 , which is similar to the relation of metal hydrides. It was presumed that the entropy of oxygen in the metal oxides and the metal peroxides, together with the entropy of hydrogen in the metal hydrides can be controlled by the thermodynamics of ideal gas. Those volume differences were increased by increasing of the work function based on the small ion binding properties. However, the absolute values of the standard enthalpy differences |Δ H | had large values at Δ V of -22 to 8 cm 3 /molO 2 . The thermodynamic stabilities which are the absolute values of the standard enthalpy differences decreased in the order, metal oxides > metal peroxides > metal hydrides. • The relation between standard entropy and volume differences Δ S, Δ V was analyzed. • |Δ S | linearly increased with ln|Δ V | below 2⊡3⊡ • The slope was approximately gas constant R. • |Δ H | had large values at Δ V of -22 to 8cm 3 /molO 2 ,Δ H standard enthalpy differences. • |Δ H | decreased in the order, metal oxides > metal peroxides > metal hydrides.