Question

Equal volume of $0.02MAgN{O}_3$ and $0.02MHCN$ were mixed. Calculate $\left[A{g}^{+}\right]$ at equilibrium. Take $K_a\left(HCN\right)=9\times {10}^{-10},K_{sp}\left(AgCN\right)=4\times {10}^{-16}$,

Answer 1

$A{g}^{+}+C{N}^{-}⟶AgCN$

$K_{sp}AgCN=\left[Ag{]}^{+}\right[CN{]}^{-}$

$[Ag{]}^{+}=\frac{K_{sp}AgCN}{C{N}^{-}}$

$[Ag{]}^{+}=\frac{4\times {10}^{-16}}{.02}=2\times {10}^{-14}$

as some $A{g}^{+}$ will precipitate out so the conc. will be reduced.