The first acidic ionization constant of Ni(II) ion as nickelous perchlorate has been determined be a potentiometric titration at constant ionic strength in sodium perchlorate solutions at temperatures ranging from 25 to 50°C. Ni(II) ion concentrations from 2 to 20 × 10−3 M have been employed. The assembled information indicates the first hydrolysis reaction of this ion is a mononuclear reaction where the complex NiOH+ is formed with ΔG298′0 = 13·25 ± 0·1 kcal/mole and ΔH298′0 = 7·76 ± 1·0 kcal/mole.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada
