Solubility of simple aluminium compounds expected in soils. II. Hydrolysis and conductance of Al3+

The results of conductimetric measurements on dilute aluminium chloride solutions at 25� were found to be best fitted by the limiting equivalent conductances A01/3Al3 + = A01/2AlOH2+ = 58.2 with the parameter for ionic diameter 6.0A and by *K1 = log [(AlOH2+)(H+)/(Al3+)] = - 5.05 when it was assumed that AlOH2+ and H+ concentrations produced by hydrolysis were equal in the measured solutions. Potentiometric measurements and calculations from solubility work gave *K1 = -5.00 and -4.97 respectively. After small changes, e.g. by aging, dilute aluminium salt solutions conform to the solubility expression for aluminium hydroxide, log [(AlOH2+) (OH-)2] = -23.31.