Chemistry 9701/43 May June 2021 | Cambridge AS Level Past Papers With Mark Scheme

1. Thermal stability trends in Group 2 hydroxides and their dissociation; solubility product (Ksp) applications to calculate calcium hydroxide solubility in water and effects of sodium hydroxide.

2. Chromium complex formation, structures of polar and non-polar ions, ligand properties of picolinic acid, decomposition of ammonium dichromate, and oxidation number changes during decomposition.

3. Transition element definitions, standard cell potential apparatus, catalytic cycles involving Fe³⁺, reaction mechanisms, and redox behavior of Fe(CN)₆³⁻ with iodide ions.

4. Reactions of [Cu(H₂O)₆]²⁺ with hydroxide and ammonia, precipitation and solubility effects, reduction of copper(I) oxide with sulfuric acid, and identification of resulting compounds.

5. Reaction kinetics of dinitrogen pentoxide decomposition; first-order reaction verification via half-life and rate constant calculation; ozone reaction mechanisms with NO₂ leading to N₂O₅ formation.

6. Acid strength comparison among carboxylic acids, alcohols, and water; proton and carbon NMR spectra for formic acid derivatives; synthesis pathways for dicarboxylic acids and diamines.

7. Synthetic routes for aromatic compounds like 3-aminobenzoic acid; peptide bond formation in amino acid mixtures; glutathione hydrolysis products and water solubility explanation.

8. Buffer action in acid-base titrations of ethanoic acid and sodium hydroxide; titration-based purity determination of ammonium vanadate; redox reactions involving MnO₄⁻ and VO₂⁺ ions.

9. Organic transformations leading to compound identification via bromination, iodination, and esterification reactions; analysis of NMR data to determine structural properties.