Chemistry 9701/42 Oct Nov 2012 | Cambridge AS Level Past Papers With Mark Scheme

1. Hydrolysis of silicon(IV) chloride and phosphorus(V) chloride with water, observations, and balanced equations. Titration analysis of iron(III) chloride and copper dissolution with \\(\\text{KMnO}_4\\): stoichiometry, concentration, and mass calculations. Bond enthalpy calculation for \\(\\text{Si}_2\\text{Cl}_6\\) reaction. Reaction balancing and redox identification for calcium silicide with water.

2. Standard electrode potential measurement for \\(\\text{Cu}^{2+}/\\text{Cu}\\) and \\(\\text{Ag}^+/\\text{Ag}\\) cells. Derivation of \\([\\text{Ag}^+]\\) using Nernst equation and \\(\\text{E}_{\\text{cell}}\\). Solubility product expression and calculation for \\(\\text{Ag}_2\\text{SO}_4\\). Distinguishing halide ions using silver halides’ colors and solubilities. Group II sulfate solubility trends.

3. Homogeneous and heterogeneous catalysis mechanisms using iron-based examples. Reaction pathway for \\(\\text{NO}_2\\), \\(\\text{SO}_2\\), and \\(\\text{O}_2\\) reaction sequence with energy labels for \\(\\Delta H\\) and activation energy steps.

4. Capsaicin reaction scheme: identification of reagents, reaction types, and functional group reactivity with \\(\\text{H}_3\\text{O}^+\\), \\(\\text{KMnO}_4\\), and \\(\\text{KCN}\\). Structural analysis for derivatives (\\(\\text{C}\\)–\\(\\text{F}\\)) and capsaicin.

5. Functional groups in compound \\(\\text{G}\\): carboxylic acid, phenol, and aldehyde. Reactions with sodium metal, bromine water, and iodine under alkaline conditions. Dye synthesis from \\(\\text{G}\\): intermediates, reagents, and product formation.

6. Protein structure bonding types: primary (peptide links), secondary (hydrogen bonds), and tertiary (ionic/disulfide). Competitive vs. non-competitive enzyme inhibition mechanisms with diagrams. DNA base pairing, strand complementarity, and bonding.

7. DNA fingerprinting process: electrophoresis technique, fragment separation, and suspect identification. Structure determination for a crime scene compound (\\(\\text{P}\\)) using mass and NMR spectra.

8. Lactic acid polymerization to PLA: fermentation conditions, stereoisomerism, and biodegradability limitations. Co-polymerization with glycolic acid, bonding between chains, and property differences from PLA.