Le Chatelier's principle states that if an equilibrium reaction is subjected to any type of stress (ex. change in concentration, temperature, pressure, etc), the reaction will proceed in the direction that offsets this stress. In this manner, the reaction will once again reach a state of equilibrium. For the formation of the iron thiocyanate complex ion, predict which direction the reaction will favor if the following stress is applied. Fe3+ (aq) + SCN- (aq) ↔ Fe(SCN)2+ (aq) TYPE OF STRESS DIRECTION OF REACTION [Reactant (R) or Product (P)] 1. [Fe3+] is decreased R / P 2. [Fe(SCN)2+] is increased R / P 3. [SCN-] is increased R / P 4. Aqueous HCl is added (**see reaction below**) R / P Fe3+ (aq) + SCN- (aq) ↔ Fe(SCN)2+ (aq) + HCl (aq) → AlCl4- (aq) yellow colorless dark red light orange The net reaction when HCl is added is: Fe3+ (aq) + 4Cl- (aq) → AlCl4- (aq)