pK a of a weak acid HA and pK b of a weak base BOH are 3.2 and 3.4 respectively. The pH of their salt AB solution at 25 o C is

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{pK}_{a}

of a weak acid

(HA)

and

{pK}_{b}

of a weak base

(BOH)

are

3.2

and

3.4

respectively. The

pH

of their salt

(AB)

solution at

25^{o} C

is

ChemistryIonic EquilibriumJEE MainJEE Main 2017 (02 Apr)

Options:

A $6.9$
B $7.0$
C $1.0$
D $7.2$

Solution:

1147 Upvotes Verified Answer

The correct answer is:

6.9

Hydrolysis of salt of weak acid and weak base

pH = \frac{1}{2} ({pK}_{w} + {pK}_{a} - {pK}_{b})

= \frac{1}{2} (14 + 3.2 - 3.4)

= 6.9

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