THE ACTIVITY COEFFICIENT OF ZINC SULPHATE FROM ELECTROMOTIVE FORCE MEASUREMENTS

Abstract
1. Electromotive forces of the cell, Zn–Hg (sat amalgam) |ZnSO4(m), Hg2SO4(s)| Hg, were measured at 25°C. in the range of the concentrations of 0.0004321 to 3 molal. 2. The electromotive force of higher dilutions is quite abnormal owing to the solubility of mercurous sulphate. 3. The mean activity coefficients of zinc sulphate for more concentrated parts were calculated by using the Cowperthwaite and LaMer’s data about dilute solutions. The potential E0 of the cell, when ion activities of zinc sulphate are hypothetically one molal, was found to be 1.37475 volt at 25°C.