Chemistry 9701/52 May June 2018 | Cambridge AS Level Past Papers With Mark Scheme

1. Preparation of Iron(III) Chloride Solution: Addressing safety precautions when handling iron(III) chloride due to skin irritation, and describing observations from the U-tube experiment that confirms the positive charge of Fe2O3 sol particles.
2. Precipitation of Fe2O3 Sol: Describing the effect of adding sulfate ions on the precipitation of Fe2O3 sol and calculating the moles of sulfate added in a small volume.
3. Preparation of Standard Solutions: Calculating the mass of potassium sulfate needed to make a standard solution of 0.100 mol dm–3, and detailing the procedure to prepare this solution accurately.
4. Concentration Dilution and Equipment: Calculating volumes for diluting K2SO4 solutions and determining the equipment needed for accurate measurement, while comparing the accuracy of dilution versus mass-based preparation methods.
5. Investigation of Salt Solutions in Precipitation: Describing how varying the charge on the anion affects the precipitation of Fe2O3 sol, identifying the independent variable, and determining the most effective salt for removing arsenic sulfide from drinking water.
6. Boiling Point Elevation Experiment: Explaining how the lowering of vapour pressure increases boiling point, using glucose in an experiment to determine the boiling point constant (Kb) for water, including analysis of anomalous points and calculation of Kb.