Chemistry 9701/31 Oct Nov 2009 | Cambridge AS Level Past Papers With Mark Scheme

1. Determination of Enthalpy Change: Procedures for determining the enthalpy change (ΔH) of the reaction between zinc and copper sulfate, including weighing zinc powder, observing temperature changes, and calculating heat energy released in the reaction.
2. Experimental Setup: Instructions for the precise weighing of zinc powder, temperature recording during the reaction, and the method for determining the amount of heat energy released.
3. Calculations and Molar Quantities: Steps to calculate the moles of copper sulfate and zinc involved, determining the limiting reagent, and calculating the heat released based on the experimental data.
4. Reagents and Excess: Identification of the limiting reagent based on the molar ratios and mass calculations, explaining the excess reagent.
5. Enthalpy Change Calculation: Detailed instructions for calculating the enthalpy change (ΔH) for the reaction, showing proper use of significant figures in the final calculations.
6. Experimental Errors: Identifying sources of experimental error and suggesting improvements for minimizing these errors in future experiments.
7. Qualitative Analysis: Tests for identifying cations and anions present in unknown samples, including reactions with NaOH, ammonia, barium nitrate, and silver nitrate to confirm the presence of specific ions.