A technician is choosing between two acid solutions for a laboratory process in which a high concentration of hydrogen ions is needed. The solutions have the same acid concentration. The technician measures their pH values.
| Sample | Acid | Concentration / mol/dm3\mathrm{mol/dm^{3}}mol/dm3 | pH |
|---|---|---|---|
| A | hydrochloric acid | 1.0 | 0 |
| B | ethanoic acid | 1.0 | 2 |
Give the sample that should be selected and explain your choice.
The technician dilutes sample A by adding water until its acid concentration is ten times smaller. Calculate the new pH of sample A. State whether its strength has changed and explain your answer.
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.