Answer: Sulfuric acid.
- A Nitric acid
- B Hydrochloric acid
- C Sulfuric acid
- D Acetic acid
Correct answer: C. Sulfuric acid
Explanation: Concentrated sulfuric acid acts as a catalyst and dehydrating agent in esterification.
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.