Chemistry 9701/51 Oct Nov 2020 | Cambridge AS Level Past Papers With Mark Scheme

1. Preparation and calculation of standard solutions, stoichiometric redox titrations involving manganate(VII) and ethanedioate, and determining the concentration of potassium manganate(VII).

2. Analysis of redox titration data to calculate the percentage of iron in iron wire, error analysis in titration measurements, and the impact of experimental conditions on Fe2+ oxidation states.

3. Ideal gas equation applications in determining the molar mass (Mr) of alkanes, graph plotting of gas volume against mass, and the analysis of anomalous data.

4. Experimental improvements and safety precautions for gas collection and analysis, identifying effects of contamination with volatile alkanes, and ensuring gas temperature uniformity to maintain calculation accuracy.

5. Practical use of sulfuric acid in redox titrations, its dual role as a reactant and medium stabilizer, and its necessity to maintain experimental accuracy.

6. Quantitative and qualitative evaluations of experimental setups for reliability, data accuracy, and identification of errors or biases in titration and gas collection methodologies.