A-LevelChemistryOrganic synthesisFeb/Mar 2023Paper 1 Q331 Mark
Citric acid can be converted into tricarballylic acid in two stages. An intermediate, Q, is formed. [Figure 33.1: Reaction scheme showing citric acid (HOOCCH₂C(OH)(COOH)CH₂COOH) converting via stage 1 to intermediate Q (HOOCCH₂CH(COOH)CH₂COOH), and then Q converting via stage 2 to tricarballylic acid (CH₂COOHCH(COOH)CH₂COOH).] Which reagents are needed for each stage? [Table with columns "stage 1", "stage 2"]
Aconcentrated H2SO4, H2(g) and Ni
Bconcentrated H2SO4, LiAlH4
CLiAlH4, H2SO4(aq)
DNaOH(aq), H2(g) and Ni
✓ Correct Answer
The correct answer is A: concentrated H2SO4, H2(g) and Ni
📋 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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