• # question_answer Following equilibrium is set up when $SC{{N}^{-}}$  ion is added to $F{{e}^{3+}}$ in aqueous solution : $\underset{Pale\,yellow}{\mathop{F{{e}^{3+}}}}\,+\underset{Colour\,less}{\mathop{SC{{N}^{-}}}}\,\rightleftharpoons \,\,\underset{Deep\,\,red}{\mathop{\,{{[Fe(SCN)]}^{2+}}}}\,$       When silver nitrate is added to the solution, $AgSCN$ gets precipitate. What will happen to the equilibrium?

Equilibrium gets displaced to the left because with removal $SC{{N}^{-}}$ ions from the equilibrium mixture, more of the deep red complex (product) will decompose into the reactants. Thus, the colour of the solution will slowly change from deep red to pale yellow.