EXAM 3 - Nguyen Anhtuan Exam 5 Due May 2 2007 noon Inst...

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Nguyen, Anhtuan – Exam 5 – Due: May 2 2007, noon – Inst: Donna C Lyon 1 This print-out should have 18 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. The due time is Central time. 001 (part 1 oF 1) 10 points Consider the voltaic cell: Pt Sn 4+ (0.0010 M), Sn 2+ (0.10 M) Ag + (0.010 M) Ag Sn 4+ + 2 e - Sn 2+ E 0 = +0 . 15 V Ag + + 1 e - Ag(s) E 0 = +0 . 80 V The electrons ±ow in the external circuit From 1. Sn 2+ to Ag + . 2. Ag to Sn 4+ . 3. Ag to Pt. 4. Sn to Ag. 5. Pt to Ag. correct Explanation: 002 (part 1 oF 1) 10 points The reaction 8H + + MnO - 4 + 5²e 2+ 5²e 3+ + Mn 2+ + 4H 2 O occuring in solution requires 36.0 mL oF 0.160 M KMnO 4 to oxidize 25.0 mL oF an ²eSO 4 solution. What is the molarity oF the ²eSO 4 solution? 1. 1.15 M correct 2. 1.95 M 3. 0.65 M 4. 3.30 M Explanation: V KMnO 4 = 36.0 mL [KMnO 4 ]= 0.160 M V FeSO 4 = 25.0 mL According to the balanced reaction, one mole oF KMnO 4 reacts with 5 moles oF ²eSO 4 . 36.0 mL oF 0.160 M KMnO 4 solution contain 0.00576 moles oF MnO - 4 , which react with 0.0288 moles oF ²e 2+ . 0.0288 moles oF ²e 2+ in 25.0 mL oF solution is a concentration oF 1.152 mol/L or 1.152 M. 36 . 0 mL × 1 L 1000 mL × 0 . 160 mol MnO - 4 L × 5 mol ²e 2+ 1 mol MnO - 4 = 0 . 0288 mol ²e 2+ 0 . 0288 mol ²e 2+ 25 mL × 1000 mL 1 L = 1 . 152 M 003 (part 1 oF 1) 10 points A voltaic (or electrochemical) cell 1. involves oxidation, which is a gain oF elec- trons. 2. converts electrical energy to chemical en- ergy. 3. involves electrolysis reactions which al- ways produce a gas at at least one electrode. 4. involves reduction, which is a loss oF elec- trons. 5. converts chemical energy to electrical en- ergy. correct Explanation: 004 (part 1 oF 1) 10 points The discharge For a lead storage battery is indicated by Pb + PbO 2 + 2H 2 SO 4 2PbSO 4 + 2H 2 O What is the highest oxidation state oF lead in the species in this equation? 1. one 2. Four correct 3. three 4. zero 5. two
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Nguyen, Anhtuan – Exam 5 – Due: May 2 2007, noon – Inst: Donna C Lyon 2 Explanation: 005 (part 1 of 1) 10 points Chlorine, bromine, and iodine are good 1. bases. 2. oxidizing agents. correct 3. reducing agents. Explanation: 006 (part 1 of 1) 10 points A mass loss of 12 . 57 g occurred in 6 hr at a titanium anode when a current of 4 . 7 A was used in an electrolytic cell. What is the oxidation number of titanium in the solution? 1.
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This note was uploaded on 07/12/2011 for the course GOV 365L taught by Professor Liu during the Spring '08 term at University of Texas.

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EXAM 3 - Nguyen Anhtuan Exam 5 Due May 2 2007 noon Inst...

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