Question

Ammonia is a weak base that reacts with water according to the equation $NH_3 (aq) + H_2O (l) \rightleftharpoons NH_4^+ + OH^- (aq)$

Will any of the following increase the percent of ammonia that is converted to the ammonium in water?

• A. Addition of NaOH.
• B. Addition of HCl.
• C. Addition of $NH_4Cl$.

Answer 1

Answer: (B)

(b) Addition of HCl.

Answer 2

The equilibrium reaction is $NH_3 (aq) + H_2O (l) \rightleftharpoons NH_4^+ (aq) + OH^- (aq)$. (a) Adding NaOH increases $OH^-$ concentration, shifting equilibrium left. (b) Adding HCl reacts with $OH^-$, removing a product, shifting equilibrium right, increasing $NH_4^+$ formation. (c) Adding $NH_4Cl$ increases $NH_4^+$ concentration, shifting equilibrium left.