Chemistry 9701/42 Oct Nov 2019 | Cambridge AS Level Past Papers With Mark Scheme

1. Electrochemical Cell Construction and Calculations: Designing an electrochemical cell with a Br2/Br- and Mn3+/Mn2+ half-cell, including using the Nernst equation to calculate electrode potential and overall cell potential, and writing the overall cell reaction.
2. Electrolysis of Copper(II) Sulfate: Using copper electrodes, calculating the Avogadro constant based on copper deposition, and understanding why magnesium metal cannot be obtained from the electrolysis of dilute aqueous magnesium sulfate.
3. Reaction Kinetics and Practical Method for Rate Determination: Identifying methods to determine reaction order with respect to hydroxide ions, and calculating the rate constant for the hydrolysis of methyl ethanoate.
4. Ammonium Chloride Solution Behavior: Calculating the pH, pKa, and behavior of ammonium chloride in solution, and explaining buffer solution behavior when acids or bases are added.
5. Thermodynamics of Reactions: Calculating entropy changes (ΔS) and temperature conditions for feasibility, and explaining the thermal stability of Group 2 carbonates.
6. Qualitative Analysis and Ionic Reactions: Identifying cations and anions in different solutions using various tests, including writing ionic equations and calculating the number of moles of water of crystallization in a hydrated salt.
7. Polymer Chemistry and Biodegradability: Understanding the synthesis and structure of a polymer from benzene-1,4-dioyl chloride and benzene-1,3-diamine, as well as the biodegradability and polymerisation mechanisms.
8. Synthesis of Butanedioic Acid: Describing the reagents and conditions needed for the synthesis of butanedioic acid and understanding its properties when oxidised or compared to other organic compounds.
9. Mass Spectrometry and NMR Spectroscopy: Using proton NMR and carbon-13 NMR spectroscopy to interpret the structure of methylpropanedioic acid and determining molecular properties.
10. Nicotinamide Structure and Reactions: Identifying delocalised electrons in nicotinamide, understanding its synthesis, and predicting reactivity with acid, alkali, and reducing agents.