Question

Find the pH of a 0.010M solution of NH4ClO4 and the pH of a 0.010M solution of NH4C2H3O2.

Answer 1

after finding the ph of the corresponding ions in these two questions, would you add the two ph's together to determine the final ph of the solution?

Answer 2

I assume these are two separate solutions; i.e., two separate problems.
The pH of the NH4ClO4 solution is determined by the hydrolysis of the salt. NH4ClO4 is the salt of a weak base (NH3) and a strong acid (HClO4), therefore, the NH4^+ is hydrolyzed.
NH4^+ + HOH ==> NH3 + H3O^+
Make an ICE table.
Plug in the numbers and calculate H3O^+ and pH from that.
For NH4C2H3O2, both NH4^+ and C2H3O2^- are hydrolyzed since that is the salt of a weak acid (HC2H3O2) and a weak base (NH3). The formula for the pH of such a solution is
(H^+) = sqrt(Kw/KaKb)