An analytical chemist prepared a standard solution of malonic acid (C3H4O4\text{C}_3\text{H}_4\text{O}_4C3H4O4) to determine the precise concentration of a potassium hydroxide (KOH\text{KOH}KOH) solution.
The chemist prepared 500 cm3500\text{ cm}^3500 cm3 of a standard solution of malonic acid with a concentration of 0.0600 mol/dm30.0600\text{ mol/dm}^30.0600 mol/dm3.
Calculate the mass of malonic acid required to prepare this solution.
Relative atomic masses (ArA_rAr): H=1\text{H} = 1H=1; C=12\text{C} = 12C=12; O=16\text{O} = 16O=16.
During the titration, 18.5 cm318.5\text{ cm}^318.5 cm3 of the 0.0600 mol/dm30.0600\text{ mol/dm}^30.0600 mol/dm3 malonic acid solution was required to completely neutralise 20.0 cm320.0\text{ cm}^320.0 cm3 of the potassium hydroxide solution.
The balanced equation for this reaction is:
2KOH+C3H4O4→C3H2O4K2+2H2O 2\text{KOH} + \text{C}_3\text{H}_4\text{O}_4 \rightarrow \text{C}_3\text{H}_2\text{O}_4\text{K}_2 + 2\text{H}_2\text{O} 2KOH+C3H4O4→C3H2O4K2+2H2OCalculate the concentration of the potassium hydroxide solution in mol/dm3\text{mol/dm}^3mol/dm3. Give your answer to 3 significant figures.
40 exam-style questions on AQA GCSE Chemistry 4.2 Reactions of acids, covering 4.2.1 Reactions of acids with metals, 4.2.2 Neutralisation of acids and salt production, 4.2.3 Soluble salts, 4.2.4 The pH scale and neutralisation, 4.2.5 Titrations, and 4.2.6 Strong and weak acids (HT only). Each one has a worked solution and a mark scheme showing where the marks go.