Chemistry 9701/31 May June 2012 | Cambridge AS Level Past Papers With Mark Scheme

1. Investigating reaction rates involving iodide and peroxodisulfate ions, experimental method for measuring time until color change, calculations for reaction rates and iodine concentration.
2. Titration calculations for sodium thiosulfate and iodine, determining the rate of reaction and moles of reactants involved, and evaluating experimental uncertainties.
3. Qualitative analysis for identifying ions using precipitation, solubility, and color change reactions, with focus on halide ions, sulfate, and chromium ions.
4. Practical considerations in determining purity of substances like calcium carbonate, and methods to reduce experimental errors, including volume measurements and reagent selection.