A-LevelChemistryAtoms, molecules and stoichiometryMay/June 2019Paper 3 Q110 Marks
Metal carbonates react with acid to produce carbon dioxide. You will determine the identity of a Group 2 metal M in a carbonate of formula MCO3 by reacting the carbonate with excess dilute hydrochloric acid and measuring the volume of carbon dioxide produced. MCO3(s) + 2HCl(aq) → MCl2(aq) + CO2(g) + H₂O(I) FA 1 is 50 cm³ of 4.00 moldm⁻³ hydrochloric acid, HCl. FA 2 is the metal carbonate, MCO3.
📋 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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