A student has 0.1 mol/dm30.1\,\mathrm{mol/dm^{3}}0.1mol/dm3 hydrochloric acid, HCl\mathrm{HCl}HCl, a strong acid, and 0.1 mol/dm30.1\,\mathrm{mol/dm^{3}}0.1mol/dm3 ethanoic acid, CH3COOH\mathrm{CH_{3}COOH}CH3COOH, a weak acid.
The student measures the pH of each acid and adds a piece of magnesium ribbon to each acid.
Which statement is correct?
Hydrochloric acid has the lower pH and reacts faster with magnesium.
Hydrochloric acid has the higher pH and reacts faster with magnesium.
Both acids have the same pH, because they have the same concentration.
Ethanoic acid has the lower pH, because each molecule contains more hydrogen atoms.
53 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.