6. To determine the concentration of SCN in our saliva, we reacted the SCN in the saliva with Fe’ according to the following reaction: We measured the absorbance of the FeSCN and used the absorbance value of the FesCN2 to obtain the concentration of the FesCN2*. This was achieved by measuring the absorbance values of standard FeSCN2+ solutions and constructing a calibration curve. We then related the FeSCN concentration to the original SCN concentration in our saliva. Answer the following questions from this experiment (a) Define Kf for the chemical reaction in the form of an equation. Why is it important that it is large for this experiment. (5 POINTS) (b) Calculate Kf from the data below knowing that eb is 6120 L/mol for FeSCN2*. Show your work. (10 POINTS) Absorbance FeSCN 0.579 mL of Fe” solution mL SCN 2.50 x 10 20.00 2.50 x 10% 5.00 (Hint: Calculate the initial concentrations of Fe and SCN first and then determine the equilibrium concentrations of Fe3*, SCN, and FeSCN2+. Calculate K, from the equilibrium concentrations) (c) Suppose a student took 400 μL of saliva and added 10.0 mL of Fe” solution in excess. If the absorbance of the sample was 0.935 and the calibration curve from my standards (in mM concentration) was y 6.204x +0.00123, calculate the approximate concentration of SCN (in mM) in the saliva. Do you think this person is a smoker? Show all calcuations. (5 Points)