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exam1 - CHEM 209 Final Exam 1 NANIE 1(20 POlNTS(a Suppose...

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Unformatted text preview: CHEM 209 Final Exam 1 2/21/05 NANIE: 1. (20 POlNTS) (a) Suppose that you are given the task of determining the SCN' content of a blood sample by forming the Fe(SCN)2+ complex and measuring its absorbence. You begin by taking a 10.00-rnL portion of the blood sample, centrifuging it, transferring 0.50 ml of the clear serum to a 10-mL volumetric flask, and filling the flask to the mark with 0.20M Fe 3+. The %T of this solution, measured at 450 nm, is 61.5%. A calibration curve, prepared from Fe(SCN)2+ standards, indicates that the Fe Concentration of this sample solution is 0.1] 1.1M. Calculate the Fe content (in M ) of the blood sample. SHOW ALL WORK CLEARLY. (Atomic weight of Fe = 55.85 gram/mole; formula weight of SCN' = 58.08 gram/mole) (b) What is the absorbance of the sample solution? 2. (40 POINTS) (a) Write the balanced chemical reaction that. occurs during the titration of N32C03 with HCl. . (b) Write the equilibrium constant expression for this reaction. K: (c) On the graph below, sketch the shape of the titration curve expected for this titration. ' mL HCl (d) If the N32C03 weight taken for the titration was 0.33 33 gram and concentration of the HCl solution was 0.096M, calculate the equivalence point volume expected. SHOW ALL WORK CLEARLY. (Formula weights: N32003 = 105.99 gram/mole; HCl = 36.46 gram/mole) ' 3. (20 POINTS) What quantities are plotted on the x- and y-axes of: x-axis yuaxis (a) a chromatogram? (b) an absorption spectrum? 4. (10 POINTS) Define the term “partition coefficient”. I .-____,______;T______m__m______Ww___mm- .. . 5. (10 POJNT S) Write the equilibrium constant expression for the following balanced chemical reaction: 6Fe2+ + 0:2072~ + 14H+ ————§ 201—3+ + 6Fe3+ + 71120 ...
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