Thermodynamics of the cell Pt | H2(p)| HCl (m)| AgCl| Ag and primary medium effects upon HCl in (glycerol  +  water) solvents

✍ Scribed by Luigi Falciola; Patrizia R. Mussini; Torquato Mussini

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 134 KB
• Volume: 33
• Category: Article
• ISSN: 0021-9614
• DOI: 10.1006/jcht.2000.0728

✦ Synopsis

The electromotive force (e.m.f.) E of the cell Pt|H 2 (p)|HCl(m) in Z|AgCl|Ag in {glycerol (G) + water (W)} solvents, Z = (G + W), up to glycerol mass fraction w G = 0.7 has been measured within the temperature range from 273.15 K to 313.15 K at HCl molalities up to 0.1 mol • kg -1 . On this basis, the standard molar e.m.f. E • m values pertaining to such solvent mixtures have been obtained, and have been combined with sparse literature data for optimization. At glycerol mass fractions up to w G ≈ 0.5, at constant temperature, E • m shows a linear dependence on the glycerol mole fraction x G and, in parallel, E • c (on the amount-of-substance concentration scale) shows linear dependence on the glycerol volume fraction ϕ G . The primary medium effect upon HCl, defined as the difference

) Z , has been considered as a function of the water volume fraction ϕ W in terms of Feakins and French's theory: this would lead to a primary hydration number n(hydr) = 2.4 for HCl, in good agreement with previous results obtained with solvents other than (glycerol + water). In this connection, some basic methodological aspects are discussed. Ancillary values of the densities ρ Z of the relevant solvent mixtures, which were hitherto unavailable and are necessary for the data processing leading to E • m , have also been measured.