A standard aqueous solution of chloroacetic acid (CH2ClCOOH\text{CH}_2\text{ClCOOH}CH2ClCOOH) is prepared by dissolving 1180 mg1180\text{ mg}1180 mg of the pure solid in distilled water and diluting to a total volume of exactly 150 cm3150\text{ cm}^3150 cm3. At 298 K298\text{ K}298 K, the pH\text{pH}pH of this solution is measured to be 2.032.032.03.
Calculate the value of KaK_{\text{a}}Ka for chloroacetic acid at this temperature. Give your answer to three significant figures. State the units of KaK_{\text{a}}Ka.
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.