Chemistry 9701/31 May June 2019 | Cambridge AS Level Past Papers With Mark Scheme

1. Identification of Group 2 Metal Carbonate: Reacting a metal carbonate, MCO3, with hydrochloric acid to produce carbon dioxide, calculating the moles of CO2, and determining the relative atomic mass (Ar) of M.
2. Preparation of Manganese Solutions: Calculating the volume of a 0.500 mol dm–3 manganese solution needed to prepare a 0.200 mol dm–3 solution and describing how to prepare the solution accurately using standard laboratory apparatus.
3. Electrode Potential Measurements: Using the Nernst equation and experimental data to calculate the electrode potential of the manganese half-cell, interpreting the relationship between manganese ion concentration and electrode potential.
4. Heating and Decomposition of Group 2 Carbonates: Describing the method for heating a metal carbonate (QCO3) to obtain the oxide (QO) and calculating the mass of CO2 produced, followed by determining the relative atomic mass of Q.
5. Qualitative Analysis for Metal Cations: Testing aqueous solutions of FA 4 and FA 5 to identify cations, using appropriate reagents and recording observations, and confirming the identity of the ions involved.
6. Reactivity of Group 2 Hydroxides and Testing for Completeness: Explaining the effects of incomplete decomposition on the calculated atomic mass, testing the complete decomposition of Group 2 carbonates, and suggesting methods for improving accuracy in the experiment.