Difficulty Verdict
This combined analysis of Paper 1C and 2C reveals a balanced paper (Difficulty Index: 3/5) that is highly accessible at the foundation level but features a steep ramp-up in difficulty for multi-step calculations and qualitative descriptive questions. While standard recalls on subatomic particles and functional groups provided easy marks, students struggled with the synthesis of experimental procedures and rigorous mathematical formatting.
Where the Marks Are Won or Lost
A staggering 32 marks were allocated to chemical calculations across both papers, covering empirical formulae, relative atomic masses, percentage yield, and titration stoichiometry. Candidates who displayed clear, step-by-step working and correct rounding secured top grades. Conversely, many dropped marks in the 6-mark qualitative analysis question in Paper 1C due to missing reagents or confusing the specific precipitates of halide ions.
Examiner Pitfalls & Observations
- The 'Covalent Bond' Trap in Giant Lattices: When explaining the boiling points of crude oil fractions or alkanes, a significant number of candidates incorrectly referred to breaking covalent bonds rather than overcoming intermolecular forces.
- Acidity Specifics: In the test for acids, simply stating "hydrogen" instead of the specific formula for the acidic ion \( \text{H}^+ \) resulted in zero marks.
- Electrolysis Details: In electrolysis explanations, candidates frequently failed to specify that the hydrogen ions are attracted to the negative cathode where they gain electrons to form hydrogen molecules.
Strategic Advice & Predictions
For upcoming sessions, prioritize masterclass practice on Titration Stoichiometry and Bond Energy Calculations, as these are consistently high-yield areas. Alcohols and Reversible Reactions/Equilibria were underrepresented in this series compared to past trends and are highly predicted to reappear in subsequent papers with significant mark allocations.