With a view of detecmining the thermodynamical properties of sulphur dissolved in molten lead, the reduction equilibrium of sulphur in liquid lead by hydrogen gas was studied at temperatures between 824°and 968°C.
It was found that the molten lead containing sulphur is regarded as an ideal solution in the range of conditions investigated. Experimentally derived equations relating to the reduction equilibrium are as follows:
S(in liq. Pb)+H₂=H₂S;K=P_H2S/P_H2·(%S) =Kp/(%S),
log K=-1, 398/T-0.504, ΔF°=6, 353+2.305T.
Combining the equations with the published ones with respect to the equilibrium constant of the formation reaction of hydrogen sulphide, the approximate equations expressed as a function of temperature for the dissociation pressure of sulphur dissolving in molten lead in the temperature range above described may be represented by the following equations:
2 S(in liq. Pb)=S₂; K´=P_S2/(%S) ²,
log K´=-12, 164/T+4.092,
ΔF°=55, 640-18.717T.
Furthermore combining the values observed with the equilibrium constants of dissociation of hydrogen sulphide calculated from the exact formula as a function of temperature the values of log K´ at experimental temperatures were computed and compared with those from the above equations and then it was found that both values at each temperature agree with each other.