Chemistry 9701/05 Oct Nov 2005 | Cambridge AS Level Past Papers With Mark Scheme

1. Preparation of equilibrium mixtures: Shaking mixtures of propanoic acid and solvent S to establish equilibrium in separate flasks, followed by titration with sodium hydroxide to determine concentrations of propanoic acid in both the aqueous and organic layers.
2. Calculation of moles and concentrations: Calculating the moles of propanoic acid in both the aqueous and organic layers after shaking, and determining the concentration in mol dm–3 for both layers.
3. Determining the correct equilibrium [removed]Kc): Using the data to compare two potential equilibrium expressions and selecting the one that matches experimental results.
4. Investigation of titration results: Identifying the correct concentration of hydrochloric acid by titration, and explaining why values of equilibrium constants may vary.
5. Planning experiments to identify solutions: Developing a method to distinguish sodium hydroxide from sulphuric acid solutions using practical steps and expected results.
6. Analysis of the remaining sulphuric acid solution concentrations: Further experiments to identify the concentration of sulphuric acid in two solutions, based on their reactions with sodium hydroxide and other indicators.