A technician prepares a methanoic acid solution and a strong acid solution with the same pH. The methanoic acid solution contains more acid per dm³. Which statement explains why more methanoic acid is needed?
Only a proportion of the methanoic acid molecules ionise, so more acid is needed to give the same hydrogen ion concentration.
Methanoic acid ionises completely, but each of its molecules releases fewer hydrogen ions than a strong acid molecule does.
The pH depends on the total concentration of acid molecules, so the weaker acid needs more molecules to give the same pH.
Methanoic acid is weak, which means it is dilute, so extra acid must be dissolved to give the same hydrogen ion concentration.
97 exam-style questions on AQA GCSE Chemistry 7.2 Reactions of alkenes and alcohols, covering 7.2.1 Structure and formulae of alkenes, 7.2.2 Reactions of alkenes, 7.2.3 Alcohols, 7.2.4a Carboxylic acids, and 7.2.4b Carboxylic acids as weak acids. Each one has a worked solution and a mark scheme showing where the marks go.