Overall Exam Verdict

The IGCSE Chemistry 0620 October/November 2024 examination papers provide a thorough and balanced test of syllabus objectives. While standard recall questions on bonding, periodic trends, and functional groups remain accessible, the extended theory and practical components place strong emphasis on multi-step mole calculations, graphical interpretation in reaction kinetics, and equilibria reasoning.

Where the Marks Lie

Major mark concentrations appear across several core domains:

  • Stoichiometry & The Mole: Multi-step titration calculations, determining limiting reagents from given masses, and converting gas volumes at r.t.p. using \(V = n \times 24\,\text{dm}^3\) and the Avogadro constant (\(6.02 \times 10^{23}\)).
  • Chemical Energetics & Kinetics: Interpretation of mass-loss curves over time, applying collision theory to explain temperature effects, and constructing correctly labelled energy profile diagrams showing \(E_a\) and \(\Delta H\).
  • Reversible Reactions & Equilibria: Predicting and justifying shifts in equilibrium position under changing temperature and pressure conditions using Le Chatelier's principle.
  • Organic Chemistry: Understanding homologous series, drawing monomer repeat units with open extension bonds for addition polymers (e.g. polystyrene), and cracking equations.
  • Experimental Skills & Qualitative Analysis: Precise cation/anion precipitation observations and multi-stage quantitative separation experimental designs.

Examiner Pitfalls & Common Traps

Candidates commonly lose marks due to:

  • Failing to draw continuation/extension bonds outside the brackets in polymer repeat unit diagrams.
  • Incomplete collision theory explanations—stating particles move faster without explicitly linking to an increased frequency of successful collisions and a higher proportion having \(E \ge E_a\).
  • Missing units or improper significant figure rounding in multi-step stoichiometry.
  • Vague observations in qualitative tests (e.g. omitting 'in excess' results or confusing amphoteric hydroxide precipitates).

Strategic Revision & Forecast

Ensure mastery over balancing ionic equations and half-equations for electrolysis at both inert and active electrodes. Practise standard 6-mark experimental design layouts focusing on step-by-step filtration, washing, drying, and percentage mass calculations.