A-LevelChemistryAtoms, molecules and stoichiometryFeb/Mar 2019Paper 3 Q215 Marks
It is possible that ores containing basic copper(II) carbonate also contain water of crystallisation. The formula of these ores would be written as xCuCO3•yCu(OH)2•zH2O. In this experiment you will heat a sample of a different basic copper(II) carbonate which will thermally decompose as shown. xCuCO3•yCu(OH)2•zH2O(s) → (x+y)CuO(s) + xCO2(g) + (y+z)H2O(g) You will use your results to determine whether this sample of a different basic copper(II) carbonate contains water of crystallisation. FA 3 is a sample of a different basic copper(II) carbonate.
📋 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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