A buffer solution contains 0.035 mol0.035\text{ mol}0.035 mol of sodium propanoate dissolved in 250 cm3250\text{ cm}^3250 cm3 of 0.120 mol dm−30.120\text{ mol dm}^{-3}0.120 mol dm−3 propanoic acid at 25 ∘C25\text{ }^\circ\text{C}25 ∘C.
A sample of 10.0 cm310.0\text{ cm}^310.0 cm3 of 1.00 mol dm−31.00\text{ mol dm}^{-3}1.00 mol dm−3 hydrochloric acid is added to this buffer solution.
Calculate the pH of the solution formed. Give your answer to 2 decimal places.
For propanoic acid, Ka=1.35×10−5 mol dm−3K_{\text{a}} = 1.35 \times 10^{-5}\text{ mol dm}^{-3}Ka=1.35×10−5 mol dm−3 at 25 ∘C25\text{ }^\circ\text{C}25 ∘C.
77 exam-style questions on AQA A Level Chemistry Acids and bases (A-level only), covering Brønsted–Lowry acid–base equilibria in aqueous solution (A-level only), Definition and determination of pH (A-level only), The ionic product of water, $K_w$ (A-level only), Weak acids and bases $K_a$ for weak acids (A-level only), pH curves, titrations and indicators (A-level only), and Buffer action (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.