Question

Procedure 1. Label four 50.0 mL volumetric flasks.)! through 4 2. Using a buret, add 10.00 ml of 2.00x10'MFeNO)D solution to each of the flasks 3. Using a buret, add 1.00 mL. 2.00 mL, 3.00 mL, and 4.00 mL of 2.00x 10 MKSCN 4. Fill each flask to the mark with 0.10 M HNO, solution. Stopper each flask and invert 5. Measure the absorbance of each solution at a wavelength of 447 nm (the absorbance reterred to in step 1 of this paut of the procedure. solution to flasks I through 4, respectively it several time to mix its contents. These solutions are your standard solutions maximum for FeSCN in the visible region of the electromagnetic spectrum). 1. Label five of your large test tubes (and/or small beakers) 1 through 5 2. Using a buret, add 5.00 mL of 2.00 x 10 MFe(NO,)s solution to each test tube or beaker referred to in step 1 of this part of the procedure. solution, to tubes/beakers 1 through 5, respectively reaction mixture in it of 10.00 mL 3. Using a buret, add 1.00, 2.00, 3.00, 4.00, and 5.00 mL of 2.00 x 10 MKSCN 4. Using a buret, add enough 0.10 M HNO, to each tube/beaker to give a total volume o Measure the absorbance of each solution at 447 nm. Data .33 0 .38 43 M% yu Calculations and Questions 1. Using the dilution equation, calculate the FeSCN& concentration in each standard solution. Note that the concentration of Fe in each standard solution is much greater than the SCN concentration. By virtue of Le Chatelier's Principle, the high Fe concentration causes the forward reaction in eqn. 2 to proceed to such a degree that essentially all the SCN has been converted to FeSCN Thus, the initial FeSCN concentration in your dilution calculations can be taken to be 2.00 x 10" M (ie, the l concentration of the KSCN solution used to prepare the standards.) Show all your calculations below. C.bolL OIL [2.00x10-31 (2) (290-y) . 2. Using Excel, graph absorbance vs. FeSCN concentration (in moles/ L). Obtain the correlation coefficient and best fit equation for it. Attach the graph to your report. . Using its absorbance and the equation for your calibration curve, calculate the concentration of FeSCN (in moles/L) in each reaction mixture. This is the equilibium concentration of FeSCN- in it. Show all your caleulations below ぬ s.wio", 01002 0u -5.bn.-s -si,.う 2. Using the method presented in lecture, calculate a value of the equilibrium constant, Ke, for each reaction mixture. (You'll have to find the initial concentrations of all reactants and products, then their equilibrium concentrations and, finally, K.) Show all your calculations below (and/or attach additional pages).

Answer 1

Fe Fe s CS Fe 3 -000936-000 으 -000136 6- 4x10 丁