Chapter 15, Problem 91E

Consider the reaction.

${\text{Fe}}^{3+}(aq)+{\text{SCN}}^{-}(aq)\rightleftharpoons {\text{FeSCN}}^{2+}(aq)$

A solution is made containing initial $\left[{\text{Fe}}^{\text{3+}}\right]=1.0\times {10}^{-3}\text{M}$ and initial $\left[{\text{SCN}}^{-}\right]=8.0\times {10}^{-4}\text{M}$. At equilibrium, $\left[{\text{FeSCN}}^{2+}\right]=1.7\times {10}^{-4}\text{M}$. Calculate the value of the equilibrium constant. Hint: Use the chemical reaction stoichiometry to calculate the equilibrium concentrations of ${\text{Fe}}^{3+}$ and ${\text{SCN}}^{-}$.