Arrange the following compounds in the correct decreasing order of their thermodynamic acidic streng — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Formic acid ($HCOOH$) is a stronger acid than benzoic acid ($C_6H_5COOH$) because the phenyl ring exerts a destabilizing cross-conjugation effect (+R) on the carboxylate group. Both carboxylic acids are significantly more acidic than phenol, which forms a resonance-stabilized phenoxide ion. Ethyl alcohol is the least acidic as its ethoxide ion lacks resonance stabilization and is destabilized by the $+I$ effect of the ethyl group. Therefore, the order is 3 > 4 > 1 > 2.