Question

A salt is one of the products of neutralization, consisting of an anion from an acid and a cation from a base. Salts can hydrolyze to form neutral, acidic or basic solutions in water. Which of the following salts would form an acidic aqueous solution: NaNO3, LiCH3COO, or (NH4)2SO4? Explain your answer and describe the H+ ion concentration for the acid and base which make up that salt.

Answer 1

This is NOT in any text book; I presume it isn't recommended as a way to explain the pH of salts in aqueous solution. The concept now uses the strength of the anion/cation but that hasn't been helpful in my teaching career; here is a method that works.
NaNO3 + HOH ==> NaOH + HNO3. Look at the products. NaOH is a strong base; HNO3 is a strong acid. Therefore, the solution is neutral since strong = strong. I can give you the new concept if you wish..
LiC2H3O2 + HOH ==> LiOH + HC2H3O2.
LiOH is a strong base; HC2H3O2 is a weak acid. Therefore the solution will be basic since strong out weighs weak. C2H3O2^-(let's use Ac^- to save typing) is hydrolyzed like this.
Ac^- + HOH ==> HAc + OH^-. Obviously releasing OH^- should make the solution basic.

(NH4)2SO4 + 2HOH ==> 2NH4OH + H2SO4. NH4OH is a weak base. H2SO4 is a strong acid. Strong out weighs weak so the solution will be acid. The other way, the NH4^+ will be hydrolyzed like this.
NH4^+ + H2O ==> NH3 + H3O^-. The release of H3O^+ would obviously make the solution acidic.
It's long but I hope this helps. I got through school remember the outlaw method until I understood enough chemistry to do it right. Take yur pick.