Chemistry 9701/23 Oct Nov 2016 | Cambridge AS Level Past Papers With Mark Scheme

1. Reactions of Group 14 Chlorides:
- Hydrolysis of a Group 14 chloride (XCl₄) to produce HCl and an oxide (XO₂). The reaction is followed by titration to determine the amount of hydrochloric acid produced.
- Titration Calculations: Determining the moles of hydrochloric acid reacted, calculating the molecular mass and relative atomic mass of the metal (X), and identifying the metal.

2. Enthalpy Change of Combustion:
- Definition and Calculation: Understanding the standard enthalpy change of combustion and calculating the heat energy released when ethanol is burned. This includes using calorimetry to calculate enthalpy changes and explaining the discrepancies between experimental and theoretical values.
- Energy Cycle: Constructing an energy cycle to calculate the enthalpy of formation for propanol (C₃H₇OH) from given combustion data.

3. Group 2 Elements and Their Compounds:
- Ionic Radii Trends: Explaining the trend in ionic and atomic radii down Group 2.
- Thermal Decomposition: Understanding the reactions of Group 2 metal salts and their behavior when heated, such as producing brown gas and white solids.
- Neutralization Reactions: Writing ionic equations for neutralization with calcium hydroxide and calcium carbonate.

4. Organic Chemistry:
- Stereoisomerism: Naming compounds and understanding stereoisomerism, drawing the two stereoisomers of a given structure.
- Reaction Mechanisms: Identifying and completing mechanisms for reactions involving halogenoalkanes, including electrophilic addition with hydrogen bromide.
- Alkene Reactions: Writing the skeletal formula for products formed by the reaction of alkenes with acidified manganate(VII).

5. Miscellaneous Organic Reactions:
- Alcohols and Aldehydes: Understanding reactions that convert alcohols into aldehydes and naming products in organic transformations.