Chemistry 9701/21 May June 2018 | Cambridge AS Level Past Papers With Mark Scheme

1. Catalysts and Their Effects: Describing how catalysts speed up reactions by providing an alternative pathway with a lower activation energy.
2. Heterogeneous Catalysts: Defining a heterogeneous catalyst as one that is in a different phase from the reactants.
3. Bond Energy Calculations: Calculating bond energies in sulfur trioxide using provided bond energy data.
4. Contact Process and Energy Diagram: Understanding energy changes and activation energy in catalyzed and uncatalyzed reactions.
5. Temperature Effects on Reaction Rates: Explaining how increasing temperature increases the rate of reaction but may reduce the equilibrium yield due to Le Chatelier's Principle.
6. Sulfuric Acid Reactions: Suggesting equations for oleum reacting with water to form sulfuric acid.
7. Acid-Base Behavior: Understanding strong Brønsted-Lowry acids and completing diagrams for sulfurous acid.
8. Crude Oil and Fractional Distillation: Explaining why different hydrocarbons have different boiling points based on molecular size and structure.
9. Cracking Hydrocarbons: Understanding why cracking is used to obtain more valuable hydrocarbons and writing equations for cracking reactions.
10. Polymerization of Ethene: Naming processes used to form poly(ethene) and explaining the environmental benefits of recycling plastics.
11. Periodicity and Element Properties: Explaining trends in atomic and ionic radii and ionization energies across Period 3, and understanding chlorine and silicon chloride reactions with water.
12. Cracking Reactions and Product Identification: Identifying reaction types and reagents for the formation of alcohols and isomeric alkenes.
13. Methylpropene and Hydrogen Bromide Reactions: Completing the reaction mechanism for producing the major product and explaining the selectivity.