A-LevelChemistryAnalytical techniquesOct/Nov 2017Paper 3 Q214 Marks
Zinc carbonate occurs in a basic form, which means that zinc hydroxide is also present. The chemical formula of basic zinc carbonate can be written as ZnCO₃.yZn(OH)₂, where y may not be an integer. In this experiment you will heat basic zinc carbonate to decompose it and use your results to determine the value of y. When basic zinc carbonate is heated, it decomposes as shown. ZnCO₃.yZn(OH)₂(s) → (1 + y)ZnO(s) + CO₂(g) + yH₂O(g) FA 5 is basic zinc carbonate, ZnCO₃.yZn(OH)₂.
📋 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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