Thermodynamic properties of liquid (lead + silver + bismuth) by a potentiometric method

Abstract

The excess partial molar thermodynamic functions of Pb, Ag, and Bi, and the excess molar thermodynamic functions in { x 1Pb+ x 2Ag+(1− x 1− x 2)Bi}(I) alloys for the range from 873 to 1073 K were determined by e.m.f. measurements of the concentration cells: Pb( l){0.01 PbCl 2 +0.99(0.583 LiCl+0.417 KCl)}( l){x 1 Pb+x 2 Ag+(1−x 1−x 2) Bi}( l) The thermodynamic quantities were estimated for three sections with constant ratios x 2 (1−x 1−x 2) equals to 1 3 , 1, and 3, but x 1 varied from 0.100 to 0.950. The excess molar Gibbs energies at 1073 K determined by the potentiometric method agree quite well with those estimated previously by us from equations of Kohler, Toop, and Bonnier, whereas the excess molar enthalpies and entropies are more negative or less positive. The excess molar Gibbs energies at 1073 K are positive over the entire composition range. This suggests that the mutual interactions between similar atoms are larger than those between different atoms. The excess molar enthalpies are negative or positive. The alloys of low x 2 show the most negative values of H m E but those with low x 1 are characterized by the most positive values of H m E. The excess molar entropies are negative except those for alloys of low x 1.