Answer: Resonance stabilisation of phenoxide ion.
- A Phenol's simply higher molecular mass compared to ethanol
- B Resonance stabilisation of phenoxide ion
- C Stronger intermolecular hydrogen bonding present in liquid phenol
- D Phenol containing a greater overall number of carbon atoms
Correct answer: B. Resonance stabilisation of phenoxide ion
Explanation: Phenoxide ion is resonance stabilised, increasing the acidity of phenol.
The phenoxide ion's negative charge spreads into the aromatic ring through resonance, lowering its energy and making phenol give up its proton more easily; an alkoxide ion (from a plain alcohol) has nowhere to delocalise the charge, making alcohols far less acidic.
Concept context
Oxygen-containing organic compounds. Understand the acidic nature of phenols, reactions of alcohols (dehydration, oxidation, esterification), and properties of ethers. Includes industrial applications and named reactions.