A Levels Chemistry (9701)•9701/12/M/J/21
Explanation
Reaction of alcohols with metal oxides forms alkoxides, strong organic bases
Steps:
- Recall that strong organic bases from alcohols are alkoxides (RO⁻), formed by deprotonation.
- Evaluate A: Acidified sodium dichromate oxidizes ethanol to ethanal or ethanoic acid.
- Evaluate B: Hot aluminium oxide dehydrates ethanol to ethene.
- Evaluate C: Sodium oxide reacts with ethanol to form sodium ethoxide (CH₃CH₂ONa).
- Evaluate D: Hydrogen chloride converts ethanol to chloroethane via substitution.
Why C is correct:
- Ethanol + Na₂O → 2CH₃CH₂ONa + H₂O; sodium ethoxide is a strong base as the alkoxide ion (CH₃CH₂O⁻) fully deprotonates water (pK_b < 0).
Why the others are wrong:
- A: Forms ethanal (neutral) or ethanoic acid (weak acid), not a base.
- B: Produces ethene, a neutral alkene hydrocarbon.
- D: Yields chloroethane, a neutral alkyl halide.
Final answer: C
Topic: Hydroxy compounds
Practice more A Levels Chemistry (9701) questions on mMCQ.me