Question

Fe3+(aq, yello) + SCN-(colerless) ≈[FeSCN]2+(aq,red) A sttudent studying this equilibrium begins with an equilibrium mixture that is light pink. 1. what change will the student observe when a solution containing Fe3+ion is added to this mixture? 2.Briefly explain how your answer to (1.) is consistent with Le Chateliers principle.

Answer 1

Fe³⁺(aq. yellow) + SCN^- (aq, colorless) <-----> [FeSCN]²⁺ (aq,red)

When a solution containing Fe³⁺ ion is added to the mixture it will react with SCN^- to form [FeSCN]²⁺, which is red in color.

According to Le Chatelier, the position of equilibrium will move in such a way as to counteract the change. That means that the position of equilibrium will move so that the concentration of Fe³⁺ ion decreases again - by reacting it with SCN^- and turning it into [FeSCN]²⁺. The position of equilibrium moves to the right.