Chemistry 9701/22 May June 2013 | Cambridge AS Level Past Papers With Mark Scheme

1. Explanation of weak bases with ammonia-sulfuric acid reaction. Contact process operating conditions and conversion of \\(\\text{SO}_3\\) to \\(\\text{H}_2\\text{SO}_4\\). Reactions of 1,3-dichloropropan-2-ol with concentrated sulfuric acid and ammonia.

2. Determination of sodium nitrate purity using back-titration: moles of reactants, mass of sodium nitrate, and percentage purity calculation. Oxidation number differences for nitrogen in \\(\\text{NaNO}_3\\) and \\(\\text{NH}_3\\).

3. Identification of elements based on chemical and physical properties (e.g., reactivity, bonding, and oxide formation). Flame colors, chloride formulas, and solution pH for Period 3 elements. Trends in melting points and dipole effects for \\(\\text{Cl}_2\\), \\(\\text{BrCl}\\), and \\(\\text{ICl}\\).

4. Reactions of crotyl alcohol with \\(\\text{Br}_2\\), \\(\\text{PCl}_5\\), hydrogen, \\(\\text{NaBH}_4\\), and acidified \\(\\text{K}_2\\text{Cr}_2\\text{O}_7\\). Skeletal formula and structural analysis of products. Empirical formula determination for a compound in blue cheese.

5. Ester identification and isomer drawing based on molecular formula \\(\\text{C}_2\\text{H}_4\\text{O}\\). Functional group testing for hydrolysis product \\(\\text{R}\\): Tollens' reagent, 2,4-DNPH, and sodium carbonate tests. Identification of the ester structure, chiral centers, and isomers.