Discussion Forum



1)

pKa of a weak acid (HA) and pKb of a weak base (BOH) are 3.2 and 3.4  respectively. The pH of their salt (AB) solution is


A) 7.2

B) 6.9

C) 7.0

D) 1.0

Answer:

Option B

Explanation:

For a salt of the weak acid and weak base.

               $pH= 7+\frac{1}{2}pK_{a}-\frac{1}{2}pK_{b}$

Given,    $pK_{a}(HA)= 32,pK_{a}(BOH)=3.4$

    $\therefore$    $pH  =7+\frac{1}{2}(3.2)-\frac{1}{2}(3.4)$

           =7+1.6-1.7 = 6.9