Chemistry 9701/22 March 2021 | Cambridge AS Level Past Papers With Mark Scheme

1. Explanation of how changes in temperature and pressure affect chemical reactions, including the Boltzmann distribution of energy and the behavior of ideal gases like krypton.
2. Calculations involving gas laws, including pressure, volume, and temperature changes for krypton, using the ideal gas law.
3. Reaction profile for the formation of krypton difluoride (KrF2), including activation energy (Ea) and enthalpy change (∆Hf), and how temperature affects reaction rates.
4. Use of chlorine (Cl2) in water purification, ionization trends across Period 3, and the effects of oxidation states in halide reactions with concentrated sulfuric acid.
5. Disproportionation of chlorine with sodium hydroxide and the bonding and structure of aluminium chloride (Al2Cl6), along with reactions of aluminium chloride with water.
6. Calculation of molecular formulas and bonding types in compounds formed by chlorine with metals, including reactions leading to products like AgCl.
7. Organic reactions of CH3Cl with Cl2, including free radical mechanisms, and identification of reagents for further reactions like the formation of dichloromethane (CH2Cl2).
8. Analysis of organic compounds found in the atmosphere of Saturn's moons, including combustion, acid-base properties, and molecular structures related to compounds like P, Q, and R.
9. Predicting bond angles in hydroxyethanal (HOCH2CHO), observing reactions with 2,4-dinitrophenylhydrazine and Tollens' reagent, and understanding oxidation to ethanedioic acid.
10. Reduction of hydroxyethanal to ethane-1,2-diol, with relevant reactions and reagents, and identification of molecules involved in similar reactions.