Chemistry 9701/42 May June 2018 | Cambridge AS Level Past Papers With Mark Scheme

1. Silicon Tetrachloride Properties: Explaining the low boiling point of SiCl4, its reaction with water, and the resulting acidic solution, including equations and visual observations.
2. Thermodynamic Calculations: Using entropy and enthalpy data to calculate the standard entropy of chlorine gas and explaining the negative entropy change for the formation of SiCl4.
3. Reaction Spontaneity: Determining the temperature at which the reaction to form SiCl4 becomes non-spontaneous using entropy and enthalpy values.
4. Iodine Monochloride Reaction: Analyzing the reaction between iodine monochloride and hydrogen gas, determining the rate law, and suggesting a reaction mechanism.
5. Electrolysis and Gas Evolution: Identifying substances liberated at the anode and cathode during electrolysis and calculating gas volumes collected during electrolysis.
6. Thermal Decomposition of Calcium Nitrate: Writing equations for the decomposition of calcium nitrate and describing the observations made during the reaction.
7. Group 2 Solubility Trends: Explaining the trend in the solubility of Group 2 sulfates down the group and describing the process of preparing barium sulfate.
8. Cobalt Complexes and Isomerism: Investigating cobalt(II) complexes, drawing tetrahedral structures, explaining why they are colored, and discussing isomerism in cobalt(III) complexes.
9. Phenol Derivatives: Describing reactions to form potassium phenoxide, the properties of 2-naphthol, and explaining the nitration mechanism for phenol.
10. Amino Acids and Peptide Bond Formation: Identifying functional groups in asparagine, drawing peptide structures, explaining buffering behavior, and discussing optical isomerism.
11. Calcitriol Chemistry: Analyzing the functional groups in calcitriol, explaining geometrical isomerism, and predicting NMR spectra and products from reactions with potassium manganate(VII).