Difficulty verdict
Taken together, J248/03 and J248/04 are a medium-to-demanding Higher Tier pair (about 3 out of 5). Roughly 40% of the marks are recall or one-step application. The remainder needs multi-step calculations, interpretation of unfamiliar data or extended reasoning. Each paper has 15 multiple-choice marks and then 75 marks of structured questions that finish with a 6-mark levels question.
Where the marks are
- Introducing chemical reactions (22 marks) is the biggest block. It covers moles, formula mass, balanced equations and gas volumes.
- Improving processes and products (18 marks) covers life-cycle assessment, extraction of metals, yield and fertilisers. Most of it is on Paper 4.
- Monitoring reactions (16 marks) and practical skills (11 marks) cover titration, rate of reaction, graph work and planning.
- Properties of materials, bonding and atomic structure together contribute about 40 marks, mostly on Paper 3.
- Organic chemistry (14 marks) is concentrated in the polymer questions on Paper 4.
Pitfalls to avoid
These points are inferred from the mark-scheme guidance, because no examiner report was supplied. Several are tied to marks being refused.
- Writing about ions when explaining why graphite conducts, or about intermolecular forces when explaining its melting point, scores zero for the whole part.
- Quoting values from a table without making a comparison earns nothing in evaluation questions.
- Rounding too early, ignoring significant figures or giving the wrong units (rate, concentration, standard form) costs the final mark.
- Giving the ratio the wrong way round, or dividing the wrong distances in Rf calculations.
- Mixing up a repeatable experiment with an accurate one, and treating a rough titration as a concordant result.
Strategy
Do the multiple-choice section in about 30 minutes. That leaves roughly 75 minutes for the 75 marks of written questions, so aim for about a minute a mark. For 6-mark questions, plan a short structure first: identify each substance or test, then give the evidence and the explanation. Always show working, because method marks and error-carried-forward credit are available. Learn the standard practical routines (titration, flame tests, anion tests, gas collection, calorimetry) as step-by-step methods.
Looking ahead
Energetics, electrolysis, predicting chemical reactions (halogens, Group 1) and the particle model had little weight this series compared with earlier years, so they are good candidates to return. Quantitative chemistry, bonding and practical analysis appear almost every year, so they are safe, high-value revision.