Question

Given initially equimolar solutions of each of the following weak acids, which solution will have the highest hydrogen ion concentration once equilibrium is established?

a. H2O

b. HClO2

c. HF

d. HClO

Answer 1

The concentrations of all given species are same.

We know that, as K a value increases dissociation of acid increases which in turn increases concentration of hydrogen ion. Hence, acid solution with highest K a value of acid will contain highest concentration of hydrogen ion.

Solution	Ka
Water	1.01 $\times$ 10 -14
HClO2	1.10 $\times$  10 -02
HF	6.8 $\times$ 10 -04
HClO	3.0 $\times$ 10 -08

From above table , it is clear that dissociation constant of HClO₂ is highest and hence its solution will contain maximum concentration of hydrogen ion at equilibrium.

ANSWER : HClO₂