A conservation laboratory tests two acid solutions used in stone cleaning.
| Solution | Acid | Concentration of acid (mol/dm³) | pH |
|---|---|---|---|
| R | hydrochloric acid | 0.0010 | 3 |
| S | ethanoic acid | 0.10 | 3 |
Before the pH values were measured, a trainee predicted that solution S would have a lower pH than solution R because it has a higher concentration of acid. Evaluate this prediction using the data and ideas about acid strength.
The laboratory dilutes solution R by making 10.0 cm310.0\,\mathrm{cm^{3}}10.0cm3 of it up to 1000 cm31000\,\mathrm{cm^{3}}1000cm3 with water.
Calculate the pH of the diluted solution. State whether the acid in the diluted solution is a strong acid or a weak acid, and give a reason.
112 exam-style questions on OCR GCSE Chemistry 3.3 Types of chemical reactions, covering 3.3.1 Oxidation and reduction in terms of oxygen, 3.3.2 Acids, alkalis and neutralisation, 3.3.3 The pH scale and measuring pH, 3.3.4 Oxidation and reduction in terms of electrons, 3.3.5 Dilute and concentrated, weak and strong acids, and 3.3.6 Hydrogen ion concentration and pH. Each one has a worked solution and a mark scheme showing where the marks go.