Question

The solubility of $AgCN$ in a buffer solution of $pH =3$ is $x .$ The value of $x$ is:
[Assume: No cyano complex is formed; $K _{ sp }( AgCN )$ $=2.2 \times 10^{-16}$ and $\left. K _{ a }( HCN )=6.2 \times 10^{-10}\right]$

• A. $0.625 \times 10^{-6}$
• B. $1.9 \times 10^{-5}$
• C. $2.2 \times 10^{-16}$
• D. $1.6 \times 10^{-6}$

Answer 1

Answer: (B)

$\frac{ K _{ sp }}{ Ka }=\frac{ s ^{2}}{\left( H ^{+}\right)} ; \quad s =\sqrt{\frac{ K _{ sp }}{ K _{ a }}\left( H ^{+}\right)}$

$s=\sqrt{\frac{2.2 \times 10^{-16}}{6.2 \times 10^{-10}} \times 10^{-3}}$

$s =1.9 \times 10^{-5}$