The overall formation constant for \(\mathrm{HgI}_{4}{ }^{2-}\) is \(1.0 \times 10^{30}\). That is,

\[1.0 \times 10^{30}=\frac{\left[\mathrm{HgI}_{4}{ }^{2-}ight]}{\left[\mathrm{Hg}^{2+}ight]\left[\mathrm{I}^{-}ight]^{4}}\]

What is the concentration of \(\mathrm{Hg}^{2+}\) in \(500.0 \mathrm{~mL}\) of a solution that was originally \(0.010 \mathrm{M} \mathrm{Hg}^{2+}\) and had \(65 \mathrm{~g}\) of KI added to it? The reaction is

\[\mathrm{Hg}^{2+}(a q)+4 \mathrm{I}^{-}(a q) ightleftharpoons \mathrm{HgI}_{4}{ }^{2-}(a q)\]