Answer
Chemical equation for the formation of this complex ion.
$Ag^+(aq) + 2CN^-(aq) \lt -- \gt [Ag(CN)_2]^-(aq)$
Formation constant expression:
$K_f = \frac{[[Ag(CN)_2]^-]}{[Ag^+][CN^-]^2}$
Work Step by Step
1. Identify the cation and the anion, and balance their coefficients:
$[Ag(CN)_2]^-$
Cation: $1 Ag^+$
Anion: $2 CN^-$
Now, write the chemical equation:
$Ag^+(aq) + 2CN^-(aq) \lt -- \gt [Ag(CN)_2]^-(aq)$
2. To write the formation constant expression:
$K_f = \frac{[Products]}{[Reactants]} = \frac{[[Ag(CN)_2]^-]}{[Ag^+][CN^-]^2}$
