The ionisation constant of an acid, K_a is the measure of strength of an acid. The K_a values of acetic acid, hypochlorous acid and formic acid are 1.74 x 10^-5, 3.0 x 10^{- 8} and 1.8 x 10^{- 4}, respectively. Which of the following orders of pH of 0.1 mol dm^{- 3} solutions of these acids is correct?

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away

An Intiative by Sri Chaitanya

Acetic acid > hypochlorous acid > formic acid

Hypochlorous acid > acetic acid > formic acid

Formic acid > hlpochlorous acid > acetic acid

Formic acid > acetic acid > hypochlorous acid

answer is D.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

More is the acidic character, more is the value of K_a. High acidic character of acid have low value of pH.

Ka value is smallest for formic acid and highest for hypochlorous acid. Therefore, the correct order of the given acids:

$Hypochlorous acid < Acetic acid < Formic acid$

Watch 3-min video & get full concept clarity

JEE

NEET

Foundation JEE

Foundation NEET

CBSE