Equilibrium formation and thermodynamic properties of gaseous silicon monosulfide

The formation of gaseous silicon monosulfide according to the reaction 1/2 SiS_2(s + 1/2 Si_(s) = SiS_(g) has been studied by the Knudsen effusion-gravimetric technique over the temperature range 863 to 1161 K. The equilibrium SiS pressure may be expressed by the equation logP _SiS(atm) = 7.205 -12,600T ⁻¹+ 0.4677 logT -4.508 × 10⁻⁴ T + 29.88T ^−1/2 The experimental free energy of the reaction may be represented by the two-term expression ΔF _{863-1161 K} ⁰ = 54,270 -38.34T Combination of these results and recent experimental data provide the standard free energy of formation of gaseous silicon monosulfide as expressed by ΔF _{863-1686 K} ⁰ = 12,740 -19.18T Si_{(s )} + 1/2 S_2(g) = SiS_(g) ΔF _{1686-2953 K} ⁰ = 640 -12.02T Si_(l) + 1/2 S_2(g) = SiS_(g)