Love Hurts Solutions with Excess Ncs - Reacted Completely to Form Fencs2+

Love HurtsSolutions with excess NCS- reacted completely to form FeNCS2+. The concentrations of the FeNCS2+ produced were used to create a graph plotting the concentration versus absorbency. The concept behind the investigation is that you can use a graph plotting wavelength and concentration to determine the concentrations of FeNCS2+ at equilibrium in subsequent trials. The graph was then used to determine the concentrations and formation constants for solutions of FeNCS2+ that were at equilibrium rather than completion and thus made less FeNCS2+ that could not be calculated through stoichiometry.The main goal in the experiment was to determine the formation constant (Kf) for the reaction between aqueous iron and aqueous thiocyanate.

Fe3+(aq) +NCS- (aq) ↔ FeNCS2+ (aq) (1)

The formation constant is the equilibrium constant for the formation of a complex ion and is calculated by dividing the product of the concentrations of the aqueous products by the product of the concentrations of the aqueous reactants.

(2)

In order to complete the experiment, knowledge of the relationship between concentration and absorbency was needed. Concentration and absorbency are directly related, as shown by the Beer-Lambert law, where A is absorbency, Ɛ is the molar absorptivity constant, b is wavelength, and C is the concentration.

A=ƐbC (3)

Solutions with excess NCS- reacted completely to form FeNCS2+. The concentrations of the FeNCS2+ produced were used to create a graph plotting the concentration versus absorbency. The concept behind the investigation is that you can use a graph plotting wavelength and concentration to determine the concentrations of FeNCS2+ at equilibrium in subsequent trials.