A 0.0500 mol dm-3 solution of a weak acid has pH=2.80\text{pH} = 2.80pH=2.80.
What is the value of KaK_{\text{a}}Ka for this acid, in mol dm−3\text{mol dm}^{-3}mol dm−3?
3.17×10−23.17 \times 10^{-2}3.17×10−2
1.58×10−31.58 \times 10^{-3}1.58×10−3
5.02×10−55.02 \times 10^{-5}5.02×10−5
2.51×10−62.51 \times 10^{-6}2.51×10−6
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.