Determination of the Equilibrium Constant Kc by Spectrophotometry: A Comprehensive Study of the Reaction Between Iron(III) and Thyocyanate Ions

Iron (III) thiocyanate complex ion [FeSCN]2+ is a complex with a deep red color and is formed by the reaction between trivalent iron ions (Fe3+) and thiocyanate ions (SCN-). In the present study, solutions of Fe3+ and HSCN with known concentrations were used and the equilibrium constant KC of the reaction was calculated so that it can be estimated where the chemical equilibrium is shifted. By measuring the absorption of the compound at the maximum wavelength (λmax), the concentrations of [Fe3+], [HSCN], and [FeSCN]2+ in the chemical equilibrium were determined. The results found for KC, indicated that the chemical equilibrium is shifted to the right, meaning the amount of products exceeded the amount of the reactants in all cases.