Suggest Prob 8_Solutions

Suggest Prob 8_Solutions - kapur (rk7259) Suggested...

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Unformatted text preview: kapur (rk7259) Suggested Problems 8 rowland (53210) 1 This print-out should have 27 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points The rate of formation of NO 2 (g) in the reac- tion 2 N 2 O 5 (g) 4 NO 2 (g) + O 2 (g) is 5 . 78 (mol NO 2 ) / L / s. What is the rate at which N 2 O 5 decomposes? 1. 2 . 89 (mol N 2 O 5 ) / L / s correct 2. 1 . 45 (mol N 2 O 5 ) / L / s 3. 11 . 6 (mol N 2 O 5 ) / L / s 4. 5 . 78 (mol N 2 O 5 ) / L / s 5. . 723 (mol N 2 O 5 ) / L / s Explanation: 002 10.0 points Consider the concentration-time dependence graph for a first-order reaction. [A] Molar Concentration of Reactant A B C Concentration- Time- At which point on the curve is the reaction fastest? 1. A + t 1 / 2 2. A correct 3. C 4. B 5. The rates are the same at all points. Explanation: Steeper portions of the graph define faster reactions. 003 10.0 points Consider the concentration-time dependence as shown below for two first order reactions. [A] Molar Concentration of Reactant Concentration- Time- Which reaction has the greatest t 1 / 2 ? 1. the reaction represented by the lower curve 2. the reaction represented by the upper curve correct 3. Unable to determine Explanation: 004 10.0 points Consider the reaction below. Which of the following is a correct expression of the rate? 1 2 S 8 ( s ) + 3 O 2 ( g )- 2 SO 3 ( g ) 1.- [SO 3 ] 2 t 2.- 4 [S 8 ] t kapur (rk7259) Suggested Problems 8 rowland (53210) 2 3. 2 [SO 3 ] t 4.- [O 2 ] 3 t correct 5. [O 2 ] 3 t Explanation: rate =- [O 2 ] 3 t = [SO 3 ] 2 t 005 10.0 points Based on the plot below, what are the units of the rate constant for this reaction? [A] (M) time (min) 1. s 1 2. M 1 s 1 3. M min 1 correct 4. M 1 min 1 Explanation: The y-axis is presented in units of concen- tration. This, together with the fact that the line has a constant slope, tells us that this is a zero order process. The x-axis tells us the time unit is minutes. 006 10.0 points Under certain conditions, the reaction 3 A + 4 B 5 C is observed to proceed at a rate of . 017 M s 1 . What is the corresponding rate of change in product C? 1. . 00566667 M s 1 2.- . 085 M s 1 3. . 017 M s 1 4. . 051 M s 1 5.- . 017 M s 1 6. . 0034 M s 1 7.- . 00566667 M s 1 8.- . 051 M s 1 9.- . 0034 M s 1 10. . 085 M s 1 correct Explanation: The given overall rate is positive which cor- responds to a forward direction as written. Product C is reacting at 5 times the stated rate of the overall reaction. C is also a prod- uct, so the concentration is INCREASING with time, which corresponds to a POSITIVE rate....
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This note was uploaded on 01/30/2010 for the course GOV 312L taught by Professor Madrid during the Fall '07 term at University of Texas at Austin.

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Suggest Prob 8_Solutions - kapur (rk7259) Suggested...

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