2008_exam_3 - CHM 3120 Exam 3 (Form Code A) November 20,...

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CHM 3120 Exam 3 (Form Code A) November 20, 2008 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) A value of zero volts is arbitrarily assigned to the standard hydrogen electrode. (2) The potentiometer used to measure cell potentials is a high impedance device. (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 anode. 2. A galvanic cell is produced as follows: Left half-cell has a Pt wire dipping into a beaker containing an equimolar mixture of Cr +2 and Cr +3 . [Cr3+ + e- ! Cr +2 E °-= –0.42 V] Right hand cell has a Tl rod immersed in 1.00 M TlClO 4 . [Tl +1 + e- ! Tl( s ) E °+= –0.336 V] What is the cell voltage? (1) -0.36V (2) +0.084V (3) -0.76V (4) +0.15V (5) other 3. All of the following are false except: (1) Junction potentials arise from the diffusion of ions that have different mobilities. (2) The ligand in a selective ion electrode membrane should have a low affinity for the analyte. (3) The glass electrode responds to [H + ] (4) We would like our selective ion electrode to exhibit high selectivity coefficients 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 25 mL of titrant has been added? Fe
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2008_exam_3 - CHM 3120 Exam 3 (Form Code A) November 20,...

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