A Levels Chemistry (9701)•9701/13/O/N/19

Explanation
Determine molecular formula of Y and match to oxidation product of primary alcohol X
Steps:
- From percentages in 100 g Y: C = 54.54/12 = 4.545 mol, H = 9/1 = 9 mol, O = 36/16 = 2.25 mol.
- Divide by smallest (2.25): C ≈ 2, H = 4, O = 1, so empirical formula C₂H₄O (mass 44).
- Molecular mass 88 ÷ 44 = 2, so molecular formula C₄H₈O₂ (butanoic acid).
- Primary alcohols oxidize to carboxylic acids (CₙH₂ₙ₊₂O → CₙH₂ₙO₂); C₄H₈O₂ from C₄H₉OH (butan-1-ol, option D).
Why D is correct:
- Butan-1-ol (primary) oxidizes to butanoic acid (C₄H₈O₂, M=88, matching composition via formula C₄H₈O₂ %C=54.55).
Why the others are wrong:
- A: Propan-1-ol oxidizes to propanoic acid (C₃H₆O₂, M=74, %C=40%).
- B: Propan-2-ol (secondary) oxidizes to propanone (C₃H₆O, M=58, %C=61.9%).
- C: Butan-2-ol (secondary) oxidizes to butan-2-one (C₄H₈O, M=72, %C=66.7%).
Final answer: D
Topic: Hydroxy compounds
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