First slide

Acidic buffer

Question

Ka for HCN is 5 × 10^–10 at 25⁰C. For maintaining a constant pH of 9, the volume of 5M KCN solution required to be added to 10 ml of 2M HCN solution is

Moderate

A

4ml
B

7.95ml
C

2ml
D

9.3ml

Solution

P^H of an acidic buffer is given by
P^H = P^K_^a + $\log \frac{[salt]}{[acid]}$
9 = 9.3 + $\log \frac{5 \times V}{2 \times 10}$
$\log \frac{1}{2} = \log \frac{5 \times V}{2 \times 10}$
⇒ V = 2 ml

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App