Question

What is pH of 50 ml 0.1 (M) $N{H}_{4}OH$ and 50 ml 0.05 (M) HCI?
$p{K}_b=4.73$

• A. 9.27
• B. 9.37
• C. 8.37
• D. 9.47

Answer 1

The correct option is A 9.27

$N{H}_{4}OH$ + HCl $\to$ $N{H}_{4}Cl+H_{2}O$
5 2.5 Milli moles before reaction
2.5 0 Milli moles before reaction
Concentration of both $N{H}_{4}Cl$ and $N{H}_3=2.5\times {10}^{-2}M$
Applying henderson's equation-2
$pOH=p{K}_b+log\frac{\left[Salt\right]}{\left[Base\right]}=4.73$
$pH=14–4.73=9.27$