Chemistry 9701/22 Oct Nov 2016 | Cambridge AS Level Past Papers With Mark Scheme

1. Mole Calculation and Titration:
- Sample Calculation: Determining the moles of hydrochloric acid (HCl) used in a reaction with a Group 2 metal and calculating the moles of calcium carbonate (CaCO₃) in a sample.
- Neutralization: Calculating the remaining amount of hydrochloric acid after reacting with sodium carbonate and determining the purity of the sample.

2. Equilibrium and Enthalpy:
- Dynamic Equilibrium: Understanding the equilibrium between dinitrogen tetraoxide (N₂O₄) and nitrogen dioxide (NO₂), including the calculation of molecular mass, mole fractions, and equilibrium constants (Kp).
- Energy Profile: Identifying enthalpy change (∆H) and activation energy (Ea) from an energy profile diagram for the N₂O₄ ⇌ 2NO₂ equilibrium.

3. Periodic Table Trends:
- Ionization Energies: Explaining trends in ionization energies across periods, including anomalies between elements like magnesium (Mg) and aluminum (Al), and phosphorus (P) and sulfur (S).
- Melting Points: Explaining trends in the melting points of elements in Period 3 and the reasons behind specific trends.

4. Organic Chemistry:
- Nomenclature and Stereoisomerism: Naming organic compounds, including those showing stereoisomerism, and drawing structural isomers.
- Reaction Mechanisms: Identifying reaction mechanisms (e.g., substitution and elimination) involving halogenoalkanes and their corresponding conditions.

5. Reactions and Identifications:
- Reactions of Methane and Chlorine: Identifying radicals produced in the reaction of methane and chlorine in the presence of UV light.
- Reaction Types: Identifying the type of reaction (e.g., oxidation, reduction, addition, substitution) in different organic reactions such as the Tollens’ test for aldehydes and the reaction of aldehydes with HCN.