Chemistry 9701/02 Oct Nov 2002 | Cambridge AS Level Past Papers With Mark Scheme

1. Molecular energy distribution and reaction rates: The Boltzmann distribution curve illustrates the spread of molecular energies, with the activation energy representing the minimum energy required for reactions. At higher temperatures, the distribution shifts, increasing the reaction rate due to more molecules having sufficient energy to overcome the activation barrier.
2. Acid-base reactions: Ethanoic acid as a weak acid reacts with ethanol to form ethyl ethanoate and water. The equilibrium constant (Kc) for this reaction was calculated using mole data and concentrations. Dynamic equilibrium was explained, and the concept of weak acids was clarified through equations.
3. Oxide reactions: Magnesium oxide (MgO) was represented with a dot-and-cross diagram. Reactions of various oxides with water and acids were analyzed to identify alkaline, acidic, and insoluble oxides. Reactions of sulphur dioxide and aluminium oxide were explained with equations.
4. Ammonia production and reactions: The Haber process for ammonia synthesis, conditions for efficient operation, and the oxidation of ammonia to nitric acid were explored, with associated equations. Urea hydrolysis and enthalpy change calculations were also performed.
5. Functional group identification: Identifying alcohols, aldehydes, ketones, and alkenes using various reagents such as acidified potassium dichromate, Fehling’s reagent, and bromine. Reactions and observations were tabulated to match compounds to functional groups.
6. Organic synthesis: Synthesis of 1-bromopentane from pentan-1-ol and its dehydration to pent-1-ene. Further reactions to prepare insect attractants from pentan-1-ol were outlined, including necessary reagents and conditions.