Proton Transfer Reactions · Paper 1 — Free Chemistry SL Practice Questions

At 25 °C, a 0.10 mol dm$^{-3}$ aqueous solution of hydrochloric acid has a pH of 1.0. Which statement correctly describes the pH of a 0.10 mol dm$^{-3}$ aqueous solution of ethanoic acid (CH$_3$COOH) at 25 °C and explains why?

A solution of sodium hydroxide, NaOH, has a concentration of $0.010 \ \text{mol dm}^{-3}$ at $25°\text{C}$. Given that $K_w = 1.0 \times 10^{-14}$ at this temperature, what is the pH of this solution?

In aqueous solution, hydrogen sulfide reacts with ammonia via a single proton transfer: $$H_2S(aq) + NH_3(aq) \rightleftharpoons HS^-(aq) + NH_4^+(aq)$$ According to Brønsted-Lowry theory, which row correctly identifies both conjugate acid-base pairs?

When sodium ethanoate ($\text{CH}_3\text{COONa}$) is added to ethanoic acid, the ethanoate ion reacts with hydronium ions present in solution: $$\text{CH}_3\text{COO}^-(aq) + \text{H}_3\text{O}^+(aq) \rightarrow \text{CH}_3\text{COOH}(aq) + \text{H}_2\text{O}(l)$$ According to Brønsted–Lowry theory, which species acts a base in this reaction, and why?