Experiment C4.2.1.1 studies the chemical equilibrium of the reaction of thiocyanate with iron. The chemical equilibrium is a dynamic equilibrium in which the starting materials and final products are present alongside one another in the reaction mixture. Under equilibrium conditions, exactly so many parts react in one direction as back in the opposite direction. In so doing, the concentrations of the participants in the reaction remain constant and their quotient is expressed as the equilibrium constant K. By adding one of the substances involved, a new equilibrium is established.
For the reaction being investigated here
the equilibrium constant can be calculated as follows: