Question

In each of the following salts, either the cation or the anion is a weak acid or a weak base. Write the chemical equation for the proton transfer reaction of this cation or anion with water:

(a) NaC₆H₅O;
(b) KClO;
(c) C₅H₅NHCl;
(d) NH₄Br.

Answer 1

The proton transfer reactions of various ions with water determine if a salt solution is acidic or basic. Salts with weak acid or base ions will hydrolyze, and the resulting reactions with water will form OH- for a basic solution or H3O+ for an acidic solution.

Step-by-step explanation:

When salts dissolve in water, their ions can react with water in a proton transfer reaction to create acidic or basic solutions, depending on the strengths of the corresponding acid and base. Here, we analyze several salts to determine the reactions of their ions with water:

• NaC6H5O (sodium phenoxide) contains the conjugate base of phenol, a weak acid. The reaction is C6H5O- (aq) + H2O (l) → C6H5OH (aq) + OH- (aq).
• KClO (potassium hypochlorite) has the conjugate base of hypochlorous acid, HOCl. The reaction is ClO- (aq) + H2O (l) → HOCl (aq) + OH- (aq).
• C5H5NHCl (pyridinium chloride) includes the conjugate acid of a weak base, pyridine. The reaction is C5H5NH+ (aq) + H2O (l) → C5H5N (aq) + H3O+ (aq).
• NH4Br (ammonium bromide) contains the conjugate acid of ammonia, which is a weak base. The reaction is NH4+ (aq) + H2O (l) → NH3 (aq) + H3O+ (aq).

The proton transfer reaction of these ions with water indicates whether the salt solution will be acidic, basic, or neutral.