Chemistry 9701/31 Oct Nov 2015 | Cambridge AS Level Past Papers With Mark Scheme

1. Redox titration of potassium manganate(VII) with potassium iodide and sodium thiosulfate, stoichiometry of iodine and manganese species, and selection of ionic equations based on experimental mole ratios.

2. Rate of reaction between sodium thiosulfate and hydrochloric acid, analysis of concentration and reaction time relationship, predictions involving sulfuric acid and varying reaction vessel sizes.

3. Identification of anions in sodium compounds using qualitative tests with barium chloride, hydrogen peroxide, and acid; ionic equation derivation for reactions involving peroxides.

4. Qualitative analysis of cations using sodium hydroxide and ammonia, including solubility properties, precipitate visibility enhancements, and ionic equation derivations for metal hydroxides.

5. Error analysis in volumetric measurements with pipettes, evaluation of experimental accuracy improvements, and percentage error calculations for calibration precision.

6. Impact of precipitate formation time on measurement reliability, interpretation of results for halide ion oxidation, and procedural adaptations for experimental consistency.