EXAM202 - Mantooth, Marlo Exam 2 Due: Feb 23 2007, 1:00 pm...

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Mantooth, Marlo – Exam 2 – Due: Feb 23 2007, 1:00 pm – Inst: Donna C Lyon 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page – fnd all choices be±ore answering. The due time is Central time. 001 (part 1 o± 1) 10 points The reaction N 2 O 4 (g) * ) 2 NO 2 (g) is at equilibrium. Increasing the pressure will have what e²ect on the equilibrium? 1. The equilibrium remains unchanged. 2. The equilibrium is shi±ted to the le±t. correct 3. The equilibrium is shi±ted to the right. Explanation: Increasing pressure shi±ts the equilibrium in the direction that produces ±ewer molecules o± gas. 002 (part 1 o± 1) 10 points Four o± the ±ollowing ±actors can a²ect the ±or- ward rate o± a chemical reaction. Which one cannot a²ect this rate? Note: The question re±ers to reaction rate, not equilibrium. 1. physical state or state o± subdivision o± solid reactants 2. presence o± a catalyst 3. temperature 4. removal o± some o± the products o± the ±orward reaction correct 5. concentration o± reactants o± the ±orward reaction Explanation: As long as reactants are present, the ±or- ward reaction can occur; the higher the re- actant concentration, the ±aster the reaction can proceed. Other ±actors which increase reaction rates are increased temperature, in- crease in sur±ace area o± solid reactants and the presence o± a catalyst. 003 (part 1 o± 1) 10 points Consider the reaction 2 HgO(s) * ) 2 Hg( ) + O 2 (g) . What is the ±orm o± the equilibrium constant K c ±or the reaction? 1. K c = [Hg] 2 [O 2 ] 2. K c = [O 2 ] [HgO] 2 3. K c = [O 2 ] correct 4. None o± the other answers is correct. 5. K c = [Hg] 2 [O 2 ] [HgO] 2 Explanation: Solids and liquids are not included in the K expression. 004 (part 1 o± 1) 10 points The frst-order rate constant is k = 3 . 4 × 10 - 3 s - 1 ±or the decomposition o± cyclobutane cyclobutane 2(ethylene) with hal±-li±e is 204 seconds. What ±raction o± a sample o± cyclobutane remains a±ter 612 seconds under the specifed conditions? 1. ±raction = 1 8 correct 2. ±raction = 1 3 3. ±raction = 1 16 4. ±raction = 1 2 5. ±raction = 1 6 Explanation: t 1 / 2 = 204 s t = 612 s a = 1 k = 3 . 4 × 10 - 3 s - 1
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Mantooth, Marlo – Exam 2 – Due: Feb 23 2007, 1:00 pm – Inst: Donna C Lyon 2 Make a chart. Time Amount left (cyclobutane = C) 0 C 204 C 2 408 C 4 612 C 8 After 612 seconds, 1 8 of the original amount of cyclobutane is left. Alternate Solution:
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This note was uploaded on 04/12/2008 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas.

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EXAM202 - Mantooth, Marlo Exam 2 Due: Feb 23 2007, 1:00 pm...

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