Test Tube # able 1. Concentrations and Absorbances Pre-Lab Calculations From Stoichiometry From Graph X-921.0nm [Felial (M) (SCN) (M) FeSCN1(M) FeSCN? (M) Absorbance 1 0.0 0.50 2 0.0000 20 0.50 0.150 3 10.000040 0.50 0.309 4 O.OOOOLO 0.50 0.609 5 0.000080 0:50 0.742 6 0.00036 0.00036 0.104 7 0.000 ble 0.00071 0.196 0.00003 0.00063 0.269 9 0.00063 0.00094 0.406 00 8 Table 2. Equilibrium Concentrations of Iron(III) & Thiocyanate and Corresponding Equilibrium Constants for Solutions 6-9 Test Tube # [Fe] (M) [SCN)., (M) . 6 7 8 9 9 AVERAGE VALUE FOR Kc = POST-LAB QUESTIONS Type your answers to questions in the spaces provided. Calculations should be handwritten on a separate piece of paper and scanned to a PDF document, a) Explain why an excess of thiocyanate is added to solutions 1-5 in part 1 of the experiment 1. b) How would the determination of the equilibrium constant Kebe affected, if excess thiocyanate had not been added in part 1? That is explain how the process of finding a numerical value for K. would be affected 2. Use the tables provided on the next page to determine the concentration of cach species initially, at "completion", and at equilibrium. a) First use the reaction conditions for test tube #13 to fill in the initial concentration for each ion in Table A b) Next fill in the concentrations for the change' and completion" rows by using the concept of limiting reactant and Le Chtelier's Principle (i.e. assume the forward reaction goes to completion) c) Now assume the reverse reaction occurs to establish equilibrium. The completion" row from Table 1 represents the 'initial conditions for the reverse reaction in Table B. Note that the extent to which this reverse reaction occurs is represented by the variable x. d) Fill in the algebraic expressions (in terms of the variable x) for the equilibrium concentrations. e) Calculate x using your experimental average value of K 1) Lastly, calculate the equilibrium concentration of FeSCN and FSCN