Chemistry 9701/42 May June 2020 | Cambridge AS Level Past Papers With Mark Scheme

1. Stability constant calculations for EDTA complexes, Gibbs free energy changes for cadmium ligand equilibria, and temperature dependence effects on equilibrium constants.

2. Solubility trends in Group 2 sulfates, decomposition temperature comparisons for peroxides, solubility product calculations for calcium iodate, and iodate(V) titration stoichiometry.

3. Transition metal complex formation, Le Chatelier's principle applications in ligand substitutions, stereoisomerism in nickel complexes, and origin of color in transition metal complexes.

4. Mechanisms of aromatic substitution, oxidation of arenes to anhydrides, phenolphthalein synthesis, acid-base indicator equilibrium calculations, and methyl orange synthesis pathways.

5. Partition coefficient principles, benzoic acid and benzophenone extraction efficiencies, synthetic pathways from benzoic acid and bromomethylbenzene to benzophenone, and NMR peak analysis for structural identification.

6. Polycarbonate polymerisation types, intermolecular forces in polymers, protein structure stabilization, DNA replication fidelity via hydrogen bonding, and degradation pathways for polymers.

7. Thermodynamic calculations for lattice energies, enthalpy of formation of zinc bromide, lattice energy trends for halides and oxides, and factors affecting their values.

8. Electrochemical cell standard potentials, fuel cell CO₂ production calculations, electrode materials for half-cells, and overall cell reaction equations for redox systems.