Abstract
Vapour pressures of PbS in the pure PbS, FeS-PbS and Cu2S-PbS systems were measured by the transportation method within a temperature range from 1115 to 1170°C, and the activities of the components in the two binary systems were calculated. Also, the phase diagrams of the FeS-PbS and Cu2S-PbS systems were determined by the DTA method to compare with the experimental date of activities.
The experimental results obtained are summarized as follows:
(1) The vapour pressure of PbS in the range of 1115-117°C was given as: log PPbS/atm=-9193/T+5.69
and the boiling point and heat of vaporization of PbS calculated from the equation of vapour pressure were 1341°C and 42. 0kcal/mol, respectively.
(2) The activities of FeS and PbS in the FeS-PbS system at 1150°C exhibited nearly the ideal behavior, and the calculated activities from the phase diagram supposing a regular solution agreed with the experimental results.
(3) The activities of Cu2S and PbS in the Cu2S-PbS system in the range of 1130-1170°C showed negative deviation from the Raoult's law, and they were little changed by differences in temperature. The activity coefficients at the infinite dilution of the components in the system were estimated 0.04 and 0.22 for Cu2S and PbS at 1150°C, respectivery.
