Chemistry 9701/31 May June 2013 | Cambridge AS Level Past Papers With Mark Scheme

1. Determination of sulfuric acid concentration using a calorimetric method; measurement of temperature changes during neutralization with sodium hydroxide, calculation of moles from heat and volume data, and graphical intersection analysis for neutralization points.

2. Verification of acid concentration via volumetric titration; preparation of diluted sulfuric acid solutions, use of sodium hydroxide as a titrant, and calculations for molar concentration using stoichiometric relationships.

3. Comparative error analysis of calorimetric and titration methods for determining acid concentration; calculation of percentage differences and identification of potential error sources, such as heat loss or reagent inconsistencies.

4. Identification of ions in solutions using qualitative analysis techniques; systematic mixing of solutions containing Pb²⁺, Cl⁻, CO₃²⁻, and CrO₄²⁻, recording observable changes like precipitation, color shifts, and solubility variations.

5. Extension of qualitative analysis to bromide ions; substitution for chloride ions in reactions, use of silver nitrate and ammonia for differentiation, and confirmation through targeted precipitation reactions.

6. Application of qualitative analysis notes; interpretation of ionic reactions using guidelines for cation and anion behavior, such as solubility differences with NaOH and reactivity with acids and metal cations.