A-LevelChemistryAtoms, molecules and stoichiometryOct/Nov 2021Paper 3 Q110 Marks
Group 1 metal carbonates have the formula M₂CO₃. The identity of the metal ion, M⁺, may be determined by a gravimetric method. The metal carbonate is reacted with excess acid and the mass of carbon dioxide given off is measured. M₂CO₃(s) + 2HCl(aq) → 2MCl(aq) + H₂O(I) + CO₂(g) FA 1 is a Group 1 metal carbonate, M₂CO₃. FA 2 is 2.0 mol dm⁻³ hydrochloric acid, HCl.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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