What will be the effect of these salts using either blue or red litmus paper on hydrolysis?

Question

(1) copper chloride (CUCl2)
(2) copper sulphate (CUSO4)
(3) Barium chloride (BaCl2)
(4) Ammonium chloride (NH4Cl)

Answer 1

CuCl₂(aq) => Cu⁺²(aq) + 2Clˉ(aq)
Clˉ(aq) + H₂O(l) => No Reaction (Theoretically Clˉ + H₂O => HCl + OHˉ. Since HCl is a strong acid and remains 100% Ionized this hydrolysis does not occur.)
Cu⁺²(aq) + H₂O(l) => Cu(OH)₂(aq) + H⁺(aq) (Kf of Cu(OH)₂ = 1/2.2 x 10ˉ²⁰ = 4.6 x 10¹⁹ leaving sufficient H⁺(aq) to give pH < 7 => Blue Litmus => Red)

The same is true for CuSO₄(aq) => Cu⁺²(aq) + SO₄ˉ²(aq)
SO₄ˉ²(aq) + H₂O(l) => HSO₄ˉ(aq) + OHˉ(aq) which is basic b/c of the OHˉ(aq) ions from the weak bisulfate ion, but Cu⁺²(aq) hydrolysis has such a high formation constant, [H⁺] > [OHˉ] and the pH of CuSO₄(aq) would be acidic; i.e., Blue Litmus => Red.

Ba(OH)₂(aq) => Ba⁺²(aq) + 2OHˉ(aq)
Ba(OH)₂(aq) is a Group IIA hydroxide and is classified as a strong base. That is, neither Ba⁺²(aq) or OHˉ(aq) ions would hydrolyze. The pH of the Ba(OH)₂(aq) would therefore depend only on the autoionization of water => H₂O(l) => H⁺(aq) + OHˉ(aq) => [H⁺] = 10ˉ⁷M => pH = -log[H⁺] = -log(10ˉ⁷) = 7.

NH₄Cl(aq) => NH⁺(aq) + Clˉ(aq)
Clˉ(aq) + H₂O(l) => No Reaction (see CuCl₂(aq) explanation)
NH₄⁺(aq) + H₂O(l) => NH₄OH(aq) + H⁺(aq) => pH < 7 => blue litmus => red.