CH302 Exam 4-solutions

CH302 Exam 4-solutions - Version 085 Exam 4 sutclie (51630)...

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Version 085 – Exam 4 – sutcli f e–(51630) 1 This print-out should have 27 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points Aluminum is more reactive than iron, yet it is used today For a variety oF applications in which iron would corrode (cans, rain gutters, etc). The reason For the corrosion durability oF aluminum is 1. aluminum does not react with oxygen. 2. all aluminum products are treated with a plastic coating. 3. very unreactive aluminum oxide Forms a thin layer on aluminum. correct 4. aluminum does not undergo oxidation. Explanation: 002 10.0 points Copper is plated on zinc by immersing a piece oF zinc into a solution containing copper(II) ions. In the plating reaction, zinc 1. loses two electrons and is oxidized. cor- rect 2. gains two electrons and is reduced. 3. loses two electrons and is reduced. 4. gains two electrons and is oxidized. Explanation: 003 10.0 points Ar e a c t i onin v o lv in gr e a c t an t sAandBi s Found to occur in the one-step mechanism: 2A+B -→ A 2 B Write the rate law For this reaction, and predict the e f ect oF doubling the concentra- tion oF either reactant on the overall reaction rate. 1. R = k [A] [B] 2 ;[A ]doub led= the rate will increase FourFold; [B] doubled = the rate will increase FourFold. 2. R = k [A] [B] 2 the rate will double; [B] doubled = the rate will increase FourFold. 3. R = k [A] 2 [B]; [A] doubled = the rate will increase FourFold; [B] doubled = the rate will increase FourFold. 4. R = k [A] 2 [B]; [A] doubled = the rate will double; [B] doubled = the rate will double. 5. R = k [A] [B] 2 the rate will double; [B] doubled = the rate will double. 6. R = k [A] 2 [B]; [A] doubled = the rate will increase FourFold; [B] doubled = the rate will double. correct 7. R = k [A] 2 [B]; [A] doubled = the rate will double; [B] doubled = the rate will increase FourFold. 8. R = k [A] [B] 2 the rate will increase FourFold; [B] doubled = the rate will double. Explanation: A 2 B rate law = ? e f ect oF doubling the concentration oF either reactant on reaction rate = ? R = k [A] 2 [B] IF [A] is doubled, R 1 = k (2 [A]) 2 [B] =4 k [A] 2 [B] R, and the rate increases FourFold. R 2 = k [A] 2 (2 [B]) =2 k [A] 2 [B]
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Version 085 – Exam 4 – sutcli f e–(51630) 2 and the rate doubles. 004 10.0 points Write the cell diagram for the reaction 2AgCl(s)+H 2 (g) 2Ag(s)+2H + (aq) + 2 Cl - (aq) . 1. Pt | H 2 (g) | H + (aq) || Cl - (aq) | AgCl(s) | Ag(s) correct 2. Ag(s) | AgCl(s) | H + (aq) || Cl - (aq) | H 2 (g) | Pt 3. Pt | Cl - (aq) | H + (aq) || H 2 (g) | AgCl(s) | Ag(s) 4. Ag(s) | AgCl(s) | Cl - (aq) || H + (aq) | H 2 (g) | Pt 5. Pt | H 2 (g) | H + (aq) || Cl - (aq) | Ag(s) | Pt Explanation: 005 10.0 points Generally, reaction rates increase when the temperature of the system is raised because 1. the activation barrier decreases as the temperature increases. 2. the bond energy of the products decreases as the temperature increases.
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This note was uploaded on 10/06/2011 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas at Austin.

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CH302 Exam 4-solutions - Version 085 Exam 4 sutclie (51630)...

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