Question

If the pKa value of acetic acid is 4.76, predict the pKa value of HCl.

(a) -7

(b) 4.2

(c) 7

(d) 10

The question was posed to me by my school teacher while I was bunking the class.

This intriguing question originated from Carboxylic Acids Chemical Reactions in section Aldehydes, Ketones and Carboxylic Acids of Chemistry – Class 12

Answer 1

The correct answer is (a) -7

For explanation: Generally, carboxylic acids are weaker acids than mineral acids like hydrochloric acid. Also, mineral acids are strong with pKa values usually less than 1. Hence, the pKa value of carboxylic acids will be higher.