Electromotive-force measurements of molten oxide mixtures. Part 8.—Thermodynamic properties of Na2O–B2O3 melts
Abstract
E.m.f. measurements of Na2O–B2O3 melts in the composition range B2O3 to Na2O·2B2O3 have been performed in which the liquid junction used in previous studies was improved by using β-alumina. The partial and total molar free energies, enthalpies and entropies of solution have been evaluated. In accordance with Krogh-Moe's treatment, the fractions of boroxol, tetraborate and the diborate group were estimated on the assumption of an ideal associated solution. The activity of Na2O seems to change along a stepwise neutralization curve, where B2O3 or equally boroxol is considered to be a polybasic acid.