Chemistry 9701/31 May June 2017 | Cambridge AS Level Past Papers With Mark Scheme

1. Determining the Relative Formula Mass of a Copper Salt:
- Involves a titration to determine the relative formula mass of a copper salt. The experiment uses excess acidified potassium iodide to produce iodine, which is then titrated with sodium thiosulfate using starch indicator.
- The experiment includes various parts such as determining the number of moles of sodium thiosulfate, iodine, and copper ions through calculations based on titration results.

2. Decomposition of Malachite:
- Malachite (copper carbonate) is heated to study its decomposition into copper oxide, carbon dioxide, and water. This part of the practical aims to determine the accepted formula for malachite by measuring the mass of copper oxide obtained and calculating the relative formula mass.
- Various calculations are involved, including determining the moles of copper oxide produced and comparing them to the accepted formula mass of malachite.

3. Qualitative Analysis:
- The third section involves analyzing salts of copper (FA 6) and performing various tests for ions and gases, recording observations such as color changes and the formation of precipitates.
- Several specific tests, including reactions with aqueous potassium iodide, sodium hydroxide, silver nitrate, ammonia, and magnesium ribbon, are used to determine the identity of the ions and the anion present in FA 6 and FA 7.

These experiments require careful observation and calculation, particularly with regards to understanding reaction mechanisms, stoichiometry, and qualitative analysis.