MCQ
In a buffer solution containing equal concentration of $B^-$ and $HB,$ the $K_b$ for $B^-$ is $10^{-10}.$ The $pH$ of buffer solution is
- A$10$
- B$7$
- C$6$
- ✓$4$
✓
Answer
Correct option: D.
$4$
d
$ (i)$ For basic buffer,
$ (i)$ For basic buffer,
$p O H=p K_{b}+\log \frac{[\text { salt }]}{\text { loase }}$
$p H+p O H=14$
$K_{b}=1 \times 10^{-10},[\text { salt }]=[b a s e]$
$p O H=-\log K_{b}+\log \frac{[\text {salt}]}{[b a s e]}$
$\therefore \quad p O H=-\log \left(1 \times 10^{-10}\right)+\log 1=10$
$p H+p O H=14$$\left[\because \text { concentration of }\left[B^{-}\right]=[H B]\right.$
$p H=14-10=4$
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