Question

The $pH$ of a $0.05\, M$ ammonia solution is $10.97$. Find the ionisation constant the conjugate acid of ammonia, $N H_{4}^{+}$. Given, $p K_{w}=14.0\, K_{b}$ for ammonia, $=1.77 \times 10^{-5}$

• A. $ 4.77\times 10^{-5} $
• B. $ 9.77\times 10^{-5} $
• C. $ 4.99\times 10^{-10} $
• D. $ 5.64\times 10^{-10} $

Answer 1

Answer: (D)

$K_{a}=\frac{K_{w}}{K_{b}}$
$=\frac{10^{-14}}{1.77 \times 10^{-5}}$
$=5.64 \times 10^{-10}$