Adding excess sulfuric acid will push the equilibrium away from the ionizaion of the alum, back to the original state. When you add the sulfuric acid, you already had a paritally ionized sulfate ion concentratio to begin with, because the KAl(SO4)2 * 12 H2O\'s sulfate ion would be hydrolyzed by the water and the base. If you add more acid of the same ion, it will push equilibrium back to wanting the sulfate ion to not want to ionize, and it will form more complexes with the KAl(SO4)2 * 12 H2O. Thus, because aluminum is part of the complexed compound, it will not hydrolyze. I hope this helps!! :) Solution Adding excess sulfuric acid will push the equilibrium away from the ionizaion of the alum, back to the original state. When you add the sulfuric acid, you already had a paritally ionized sulfate ion concentratio to begin with, because the KAl(SO4)2 * 12 H2O\'s sulfate ion would be hydrolyzed by the water and the base. If you add more acid of the same ion, it will push equilibrium back to wanting the sulfate ion to not want to ionize, and it will form more complexes with the KAl(SO4)2 * 12 H2O. Thus, because aluminum is part of the complexed compound, it will not hydrolyze. I hope this helps!! :).