2009_exam_3 - CHM 3120 Exam 3(Form Code A Instructions On...

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CHM 3120 Exam 3 (Form Code A) November 19, 2009 Instructions: On your scantron sheet enter your name, UF ID number (start on the first space and leave the last space blank), and Form Code (see above). This exam consists of 20 multiple choice questions each worth 10 points for a total maximum of 200 pts. You may retain your exam sheet. Turn in only the scantron. Bubbling errors of any kind will count as an incorrect response. 1. Which of the following statements is not true? (1) An oxidizing agent loses electrons in a redox reaction. (2) A current of one ampere represents one coulomb per second. (3) For M + + e- ! M (s) an E o of -2.5v means M (s) is a good reducing agent. (4) The electrode at which reduction occurs is defined as the cathode. . 2. A voltaic cell involves the following reaction: Br 2 (aq) + Zn (s) ! Zn +2 (aq) + 2 Br - (aq) E o cell = 1.83v E o bromine Br 2 + 2e ! 2 Br - = 1.07v What is E o zinc Zn +2 + 2 e ! Zn s ? (1) -1.36V (2) +02.90V (3) -0.76V (4) -1.50V (5) other 3. All of the following are true except: (1) The potential of a SCE is constant because the [Cl - ] does not change. (2) The glass pH electrode is an ion selective electrode. (3) The glass electrode responds to [H + ] (4) Ligands in ion selective electrode membranes must have a high affinity for the analyte. 4. For the titration of 25 mL of 0.050 M Sn +2 with 0.100 M Fe +3 in 1 M HCl using a Pt electrode and a calomel reference electrode, what is the potential after 20 mL of titrant has been added? Fe +3 + e - ! Fe +2 E o = +0.732V Sn +4 + 2e - ! Sn +2 E o = +0.139V [E(calomel) = +0.241V] (1) -0.084 (2) +0.157V (3) +0.096V (4) -0.12V (5) other 5. In the redox titration of Sn +2 with Fe +3 (see # 4 above), which statement is not true? (1)
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This note was uploaded on 03/31/2010 for the course CHM 3120 taught by Professor Harrison during the Spring '08 term at University of Florida.

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2009_exam_3 - CHM 3120 Exam 3(Form Code A Instructions On...

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