Chemistry 9701/31 May June 2021 | Cambridge AS Level Past Papers With Mark Scheme

1. Determining the value of x in hydrated iron(II) sulfate (FeSO4•xH2O) using titration with potassium manganate(VII), including mass and molar calculations.
2. Addressing experimental considerations such as the impact of oxidation on the calculated value of x, and the need for accuracy in the titration procedure.
3. Gravimetric method for determining the value of y in a hydrated compound MZ•yH2O, including calculations of the moles of water lost and the mass of the residue.
4. Suggesting improvements for experimental procedures, including heating with a lid and ensuring complete decomposition.
5. Conducting qualitative analysis on various cations and anions, including testing for reactions with ammonium thiocyanate and identifying specific ions based on observed results.
6. Preparing and carrying out titrations with potassium manganate(VII) and sulfuric acid, including the calculation of ion concentrations and percentage by mass of ions.