An environmental chemist is studying the degradation of organic pollutants in acidic waterways. To simulate these conditions, they prepare a model buffer solution at 25 ∘C25\text{ }^\circ\text{C}25 ∘C by dissolving 1.20 g1.20\text{ g}1.20 g of solid sodium hydroxide in 250 cm3250\text{ cm}^3250 cm3 of a 0.480 mol dm−30.480\text{ mol dm}^{-3}0.480 mol dm−3 solution of methanoic acid (HCOOH\text{HCOOH}HCOOH).
Calculate the pH of the resulting buffer solution, giving your answer to 2 decimal places. For methanoic acid, Ka=1.78×10−4 mol dm−3K_a = 1.78 \times 10^{-4}\text{ mol dm}^{-3}Ka=1.78×10−4 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.