A student adds calcium hydroxide powder, 0.10 g at a time, to 50.0 cm3\mathrm{cm^{3}}cm3 of dilute hydrochloric acid. She measures the pH after each addition.
| Total mass of calcium hydroxide added in g | 0.00 | 0.10 | 0.20 | 0.30 | 0.40 | 0.50 | 0.60 |
|---|---|---|---|---|---|---|---|
| pH | 1.0 | 1.1 | 1.3 | 1.7 | 11.8 | 12.2 | 12.3 |
She repeats the experiment using 25.0 cm3\mathrm{cm^{3}}cm3 of hydrochloric acid that has twice the concentration in g dm−3\mathrm{g\,dm^{-3}}gdm−3. Between which total masses of calcium hydroxide will the pH now pass 7?
0.075 g and 0.10 g
0.15 g and 0.20 g
0.30 g and 0.40 g
0.60 g and 0.80 g
44 exam-style questions on Edexcel GCSE Chemistry 4.1 Acids, covering 4.1.1 Acids, alkalis and the pH scale, 4.1.2 Hydrogen ion concentration and pH, 4.1.3 Dilute and concentrated, weak and strong acids, 4.1.4 Bases, alkalis and the reactions of acids, 4.1.5 Chemical tests for hydrogen and carbon dioxide, 4.1.6 Neutralisation as a reaction of acids with bases, 4.1.7 Preparing soluble salts, and 4.1.8 Solubility rules and preparing insoluble salts. Each one has a worked solution and a mark scheme showing where the marks go.