# Chapter 17 - Questions and Problems - Page 824: 17.2

(a) pH increase. (b) pH decrease. (c) pH increase. (d) No change. (e) No change.

#### Work Step by Step

(a) and (c) (i) $CH_3COOH(aq) + H_2O(l) \lt -- \gt CH_3COO^-(aq) + H_3O^+(aq)$ (ii) $HCOOH(aq) + H_2O(l) \lt -- \gt HCOO^-(aq) + H_3O^+(aq)$ - According to Le Chatelier's principle, if we add (i) acetate ions or (ii) formate ions, the equilibrium will try to consume the products, therefore reducing the $H_3O^+$ concentration and increasing the pH. (b) $NH_3 (aq) + H_2O(l) \lt -- \gt NH{_4}^+(aq) + OH^-(aq)$ - According to Le Chatelier's principle, if we add ammonium $(N{H_4}^+)$, the equilibrium will try to consume the products, reducing the $OH^-$ concentration, thus decreasing the pH. (d) and (e) $HCl(aq) + H_2O(l) -- \gt Cl^-(aq) + H_3O^+(aq)$ $HI(aq) + H_2O(l) -- \gt I^-(aq) + H_3O^+(aq)$ Since $HCl$ and $HI$ are strong acids, the addition of conjugate bases will not affect the equilibrium because it is already very products-favored.

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