What is the concentration of Ba(OH)2(aq)\text{Ba(OH)}_2\text{(aq)}Ba(OH)2(aq), in mol dm−3\text{mol dm}^{-3}mol dm−3, that has a pH\text{pH}pH of 12.45 at 40 ∘C40\ ^\circ\text{C}40 ∘C?
At 40 ∘C40\ ^\circ\text{C}40 ∘C, the ionic product of water, Kw=2.92×10−14mol2dm−6K_{\text{w}} = 2.92 \times 10^{-14} \text{mol}^2 \text{dm}^{-6}Kw=2.92×10−14mol2dm−6.
1.41×10−21.41 \times 10^{-2}1.41×10−2
2.82×10−22.82 \times 10^{-2}2.82×10−2
4.11×10−24.11 \times 10^{-2}4.11×10−2
8.23×10−28.23 \times 10^{-2}8.23×10−2
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.