2018 · Q10
Which of the following statements about carboxylic acids is/are correct?
- 1Simple aliphatic carboxylic acids are soluble in water.
- 2Higher carboxylic acids are practically insoluble in water.
- 3The acidity of a carboxylic acid depends on the number of carbon atoms present in the hydrocarbon chain.
Select the correct answer using the code given below.
general-sciencechemistry
- A1 and 2 only
- B2 and 3 only
- C1 only
- D1, 2 and 3
Explanation
Short-chain aliphatic acids (formic, acetic) hydrogen-bond with water and are soluble (statement 1 true), while long-chain fatty acids are dominated by the hydrophobic tail and are practically insoluble (statement 2 true). Acidity weakens as the alkyl chain lengthens, because the electron-donating alkyl group destabilizes the carboxylate anion — so acidity does depend on the number of carbons (statement 3 true). All three statements are therefore correct.