Question

$A{g}^{\oplus }+N{H}_3\rightleftharpoons \left[Ag\right(N{H}_3){]}^{+},K_1=3.5\times {10}^{-3}[Ag(N{H}_3{)}^{+}+N{H}_3\rightleftharpoons Ag(N{H}_3{)}_2{]}^{+},K_2=1.7\times 1{-}^{-3}$ Then the formation constant of $\left[Ag\right(N{H}_3{)}_2{]}^{+}$ is :

• A. $6.08\times {10}^{-6}$
• B. $6.08\times {10}^6$
• C. $6.08\times {10}^{-9}$
• D. None of the above

Answer 1

The correct option is A $6.08\times {10}^{-6}$

$K_1=\frac{\left[Ag\right(N{H}_3){]}^{+}}{\left[A{g}^{+}\right]\left[N{H}_3\right]}=3.5\times {10}^{-3}$

$K_2=\frac{\left[Ag\right(N{H}_3{)}_2{]}^{2+}}{\left[Ag\right(N{H}_3\left){]}^{+}\right[N{H}_3]}=1.7\times {10}^{-3}$

$K_f=\frac{\left[Ag\right(N{H}_3){]}^{2+}}{\left[A{g}^{+}\right][N{H}_3{]}^2}$

The formation constant $K_f=K_1\times K_2=3.5\times {10}^{-3}\times 1.7\times {10}^{-3}=6.08\times {10}^{-6}$