Chemistry 9701/42 May June 2013 | Cambridge AS Level Past Papers With Mark Scheme

1. Hydrolysis of R–Br with NaOH: reaction type, rate determination using concentration-time graphs, calculation of reaction orders for R–Br and NaOH, and rate constant evaluation.
2. Reaction pathway diagram for NO + Br₂ → 2NOBr, including enthalpy changes and activation energy values.
3. Standard hydrogen electrode description, standard cell potential calculation for Cr²⁺ and Cr₂O₇²⁻ reaction, and observations during the reaction completion.
4. Buffer solution preparation with CH₃COOH and CH₃COONa; pH-based calculations for solution proportions and equations for reactions with added HCl and NaOH.
5. Nitration of methylbenzene and phenol: reagents, intermediate ions, and conversion of nitrobenzene to phenylamine using reducing agents.
6. Transition metal oxidation states and coloration in complexes due to d-orbital splitting, contrasted with s-block element properties; redox reactions of SO₂ and MnO₄⁻, and NH₃ reaction observations with Cu²⁺.
7. Analysis of chlorogenic acid: molecular formula, chiral centers, reaction products with Na and NaOH, stereoisomerism in products, and identification of functional groups reactive with Na₂CO₃ and Br₂.
8. Mass spectrometry and NMR applications for compound L, including peak analysis for isotopic and structural identification, fragmentation differences for propene and cyclopropane, and proton environment distinctions.
9. Hydrogel chemistry: polymer and cross-linking structures, polymerization type, recyclability based on hydrophilic properties, effects of cross-linking on mechanical properties, and molecular by-products from cross-linking.