Re-determination of the standard electrode potential of zinc and mean molal activity coefficients for aqueous zinc chloride at 298.15 K

The e.m.f. of the cell Zn–Hg(2-phase)|ZnCl2(aq.)Agcl, Ag has been measured using zinc chloride solutions in the concentration range 1.0 × 10–4–1.0 mol kg–1 at 298.15 K. Stable potentials in very dilute solutions have been obtained by use of amalgamated zinc rod (in place of liquid amalgam). The standard potential of the cell, E°, is 984.28, σ= 0.15 mV, from which E°Zn=–761.94, σ= 0.15 mV, and was obtained by two independent methods. The solutions show significant complex formation at concentrations above 0.01 mol kg–1. Mean molal activity coefficients have been calculated at concentrations up to 1.0 mol kg–1.