Decomposition and Thermodynamic Properties of Sn 2 S 3

Knudsen effusion studies of the decomposition of Sn 2 S 3 (s) have been performed employing mass spectrometry in the temperature range 669‐763 K and vacuum microbalance techniques in the range 677 ‐ 820 K yielding pressures from about 10 −2 to 10 Pa. The results demonstrate that Sn 2 S 3 (s) decomposes under present experimental conditions according to the reaction Sn 2 S 3 (s) = 2SnS(s) + 1/2 S 2 (g). The mean values for the third‐law heat and second‐law entropy of reaction based on direct mass‐loss data are ΔH° 298 = 114.0 ± 3.0 kJ/mol and ΔS° 298 = 97.3 ± 3.5 J/ K · mol. From these data the standard heat of formation and absolute entropy of Sn 2 S 3 (s) are calculated to be −254.5 ± 6.0kJ/mol and 170.5 ± 6.0 J/K · mol, respectively.