DILATOMETER STUDIES OF THE APPARENT MOLAR VOLUME LIMITING LAW FOR HIGH-CHARGE ELECTROLYTES

A continuous-dilution dilatometer, of the tilting type, specifically designed for study of the apparent molar volumes of aqueous electrolytes at low concentrations, is described. Results at 298 · 16 K have been secured for multivalent (± 3, ± 4, ± 6) univalent electrolytes which demonstrate that the apparent molar volumes vary with c1/2 in approximate conformity with the Debye-Hückel limiting-law slopes. Data are presented for: [Co(en)3] Cl3, K3 [Co(CN)6], [Pt(en)3] Cl4, K4 [Mo(CN)8], [Co((OH)2Co(en)2)3] (NO3)6, Na6C6(COO)6, K5[Fe(CN)6] and [Co(en)3] (ClO4)3. Ion pairing is a significant disturbing factor which hinders treatment of the data in terms of extended forms of the Debye-Hückel equation. © 1979, CSIRO. All rights reserved.