Measuring an equilibrium constant

In this experiment we investigate the following equilibrium:

Ag⁺(aq) + Fe²⁺(aq) Ag(s) + Fe³⁺(aq)

Silver nitrate solution is mixed with iron(II) sulfate solution, and left overnight so that equilibrium can become established. The concentration of silver ions at equilibrium is measured by titration. You may wish to review the titration theory. The potassium thiocyanate reacts with the silver ions forming a precipitate of silver thiocyanate. When the silver ions are used up a reaction then takes place between the thiocyanate and iron(III) ions producing the deep red end point. The concentrations of the other aqueous ions can be worked out knowing their original concentrations. Watch the video then use the following expression in order to work out a value for the equilibrium constant:

Video - measuring an equilibrium constant

Calculation of the equilibrium constant