Chemistry 9701/35 Oct Nov 2015 | Cambridge AS Level Past Papers With Mark Scheme

1. Ionic equation for the reaction of potassium manganate(VII) with potassium iodide, titration with sodium thiosulfate, and determination of iodine produced. Calculation of moles of reactants and products, verification of iodide oxidation, and percentage error analysis in pipette usage.

2. Effect of hydrochloric acid concentration on the rate of reaction with sodium thiosulfate, reaction time measurements, calculation of rates of reaction, initial acid concentrations, and comparison with sulfuric acid reaction rates. Influence of reaction vessel size on experimental outcomes.

3. Identification of anions in sodium compound (FA6) through qualitative tests using barium chloride, hydrogen peroxide, sulfuric acid, sodium hydroxide, and potassium manganate(VII). Equation formulation for specific reactions and observation recording for precipitate solubility.

4. Identification of cations in solutions (FA7–FA10) using sodium hydroxide and ammonia, observation of precipitate solubility, and formulation of ionic equations. Method adjustment for enhanced visibility of precipitates without additional apparatus.