Thermal decomposition of (NH₄)₂MoS₄ and (NH₄)₂WS₄heat of formation of (NH₄)₂MoS₄

Abstract

Abstract The reactions (NH 4 ) 2 MeS 4 = 2 NH 3 + H 2 S + MeS 3 (Me = Mo, W) were investigated by measuring the decomposition vapour pressures. Thermochemical data were obtained from these measurements: ΔH = 52 kcal/mole and ΔS = 105 cal/deg.mole for the decomposition of the tetrathiomolybdate. Similarly, ΔH = 69 kcal/mole and ΔS = 106 cal/deg.mole were obtained for the decomposition of the tetrathiotungstate. The normal heat of formation of (NH 4 ) 2 MoS 4 was found to be ΔH = −140 kcal/mole. The kinetics of thermal decomposition of the above reactions were also measured.