Chemistry 9701/32 May June 2021 | Cambridge AS Level Past Papers With Mark Scheme

1. Titration of Sodium Carbonate: Determining the value of x in the hydrated sodium carbonate formula (Na2CO3•xH2O) by titrating a solution of sodium carbonate with hydrochloric acid.
2. Calculations for Titration: Performing calculations for moles of hydrochloric acid, concentration of sodium carbonate, and determining the percentage of water of crystallization (x value).
3. Energy Change in Sodium Carbonate Dissolution: Measuring the heat energy released when anhydrous sodium carbonate dissolves in water, calculating moles, and determining purity from energy data.
4. Experimental Design: Suggestions for improving accuracy in experiments, such as ensuring complete dissolution and addressing impurities in samples.
5. Qualitative Analysis: Testing for cations and anions in unknown samples through various reactions, such as adding sulfuric acid, sodium carbonate, and magnesium chloride to solid samples.
6. Identifying Ions: Using test results to identify the cations and anions in different sample solutions and writing relevant ionic equations for reactions.