Studies on the Behaviour of Bibivalent Salts in Aqueous Solution : Part II. Zinc Sulphate

Six types of cells using zinc sulphate alone and zinc sulphate mixed with potassium sulphate, with and without liquid junction potentials, have been studied in order(i) to test whether activity coefficient of single ions can be roughly calculated and used in the study of equilibria, (ii) to see if Zn(SO₄)₂^2- ions are present in zinc sulphate solutions upto 0.1 M and (iii) to measure the value of dissociation constant(K) of zinc sulphate into zinc and sulphate ions. The conclusion regarding (i) is positive and (ii) is negative. Values of K are given by all the cells. The most probable value obtained from Hg_y Zn_x I ZnSO₄ Hg₂SO₄ I Hg, by extrapolating the value to zero concentration is 7.5 X 10^-3.