Chemistry 9701/41 May June 2020 | Cambridge AS Level Past Papers With Mark Scheme

1. Cobalt complex chemistry, including reaction products with NaOH and NH3, stereoisomerism in [Co(NH3)3Cl3], tetradentate ligand interactions with Co(II), and equilibrium shifts in [CoCl4]2−.

2. Trends in Group 2 hydroxides' solubility and decomposition temperatures, explained by lattice energy and hydration enthalpy differences.

3. Photosynthesis redox equations, measurement of electrode potentials for O2, standard cell calculations, and positive electrode identification.

4. Comparative basicity of nitrogen-containing compounds, preparation methods for C6H5CH2NH2 via nucleophilic substitution, and mechanisms of halide replacement.

5. Electrophilic substitution in benzene, mechanisms of bromination using AlBr3, reactivity differences in phenol versus benzene, and NMR analysis of Friedel-Crafts products.

6. Relative acidities in chloropropanoic and propanoic acids, equilibrium constant calculations using Ka values, dissociation steps of ethanedioic acid, and organic acid differentiation through chemical tests.

7. Solubility product (Ksp) expressions for Ag2CO3, Ag+ concentration calculations, carbonate ion equilibrium in silver nitrate solutions, and electrode potentials using the Nernst equation.

8. Buffer solution concepts using NH4+/NH3, pH calculations for ammonium-based buffers, and equations showing buffering reactions.

9. Catalysis mechanisms in H2O2 decomposition by MnO2, rate equations for first-order reactions, and reaction mechanisms involving iodide ions and hydrogen peroxide.

10. Transition element oxidation states, reasons for variable oxidation states compared to s-block elements, and enzymatic catalysis with transition metal complexes.