Chemistry 9701/51 Oct Nov 2017 | Cambridge AS Level Past Papers With Mark Scheme

1. Sodium Oxide and Iodine Reaction: Preparing solutions for the reaction of iodide and persulfate ions to measure the time for iodine production, and explaining the steps to calculate the mass of ammonium persulfate required for a standard solution.
2. Titration Method: Describing the procedure for preparing and using standard solutions, discussing the importance of starch as an indicator, and completing titration tables with correct volumes and concentrations.
3. Rate of Reaction: Using experimental data to calculate the rate of iodine production, assessing the reliability of results, and calculating the percentage error in volume measurements.
4. Experimental Errors: Identifying potential errors such as premature reactions and explaining their effects on the results.
5. Chemical Safety: Suggesting relevant safety precautions for handling hazardous chemicals such as ammonium persulfate, including rationale for minimizing health risks.
6. Faraday Constant Calculation: Using experimental data to calculate the volume of hydrogen gas produced, the charge passed, and deriving the Faraday constant from the reaction.
7. Electrolysis Experiments: Plotting relationships between volume and charge passed, assessing the reliability of data, and calculating moles of hydrogen gas produced per coulomb.
8. Electrolysis Observations: Predicting the effects of using copper electrodes in electrolysis and explaining how this would influence the volume of gas produced at both the cathode and anode.