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+2H2O2\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+2H2O
Calculate the concentration of the potassium hydroxide solution in mol/dm3\text{mol/dm}^3mol/dm3. Give your answer to 3 significant figures.