May/June 2025 Examiner Review & Student Performance Breakdown

The May/June 2025 Chemistry (9701) exam series presented a highly balanced suite of papers that closely aligned with the updated syllabus guidelines. Paper 12 challenged students on foundational physical ideas and conceptual trends, while Paper 22 demanded precise drawing skills for organic reaction mechanisms and multi-step pathway calculations. Paper 32 evaluated key practical competencies in volumetric titration and energetic enthalpy change determinations.

Where the Marks Were Won & Lost

Across the papers, higher-achieving students secured significant advantages on multi-step analytical calculations and organic structures. Key successes were seen in:

  • Calculating the relative isotopic mass of iron using percentage abundances.
  • Constructing step-by-step calculations to find the percentage of vitamin C in lemon juice.
  • Drawing the accurate skeletal structure of alkene Z from complex oxidative cleavage products.
Conversely, many students lost accessible marks due to avoidable formatting errors. In Paper 32, failing to maintain consistent decimal places on raw balance and thermometer readings (such as recording values to either 0.1 or 0.5 °C accuracy) resulted in severe penalties. In Paper 22, students struggled with the classic electrophilic addition mechanism of propene and HBr, frequently failing to show curly arrows originating precisely from the electron-rich double bond or the H-Br covalent bond.

Crucial Examiner Pitfalls & Misconceptions

Examiners highlighted several persistent misconceptions that occurred in both MCQ and structured questions:

  • Melting Point vs. Covalent Bond Strength: Many candidates incorrectly assumed that covalent bonds must be broken to melt molecular oxides like \( \text{SO}_2 \) or \( \text{H}_2\text{O} \), ignoring the role of weaker intermolecular forces.
  • Acidic Gas Production from Alcohols: In organic synthesis, students frequently confused the reactions of primary alcohols with phosphorus halides, failing to recognize that \( \text{PCl}_5 \) or \( \text{SOCl}_2 \) react rapidly to generate acidic hydrogen chloride gas.
  • Incorrect Reduction Stoichiometry: When showing the reduction of propanoic acid with \( [\text{H}] \), students often missed that four moles of atomic hydrogen are required to produce propan-1-ol and water.

Effective Revision & Exam Strategy

To maximize success in subsequent sittings, candidates must treat physical and organic pathways as interconnected concepts. Practice drawing full, step-by-step mechanisms with careful attention to dipole charges and intermediate carbocations. For practical exams, master the correct layout of quantitative results tables, ensuring every single titration and temperature reading is recorded to the exact level of precision required by the apparatus.

Upcoming Exam Series Prediction

Based on the relative weightings in the 2025 series, upcoming sets are highly likely to shift their focus towards Transition Metal complex equilibria, Group 17 reactions with concentrated sulfuric acid, and nitrogen-containing compounds such as amides or amino acids. Thorough revision of these core topics is strongly recommended to secure top bands in future papers.