Hwk 11 Solutions

Hwk 11 Solutions - kapur (rk7259) Homework 11 Lyon (52380)...

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kapur (rk7259) – Homework 11 – Lyon – (52380) 1 This print-out should have 20 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. This HW assignment is due Tuesday, April 28, by 11PM. 001 10.0 points ±or the reaction 2 H 2 (g) + O 2 (g) 2 H 2 O(g) fnd the value For the work done at 300 K. 1. 7.5 kJ 2. - 2 . 5 kJ 3. 2.5 kJ correct 4. - 7 . 5 kJ Explanation: T = 300 K R = 8 . 314 J mol · K w = - P Δ V = - Δ nRT = - (2 - 3) mol p 8 . 314 J mol · K P (300 K) = 2494 . 2 J 002 10.0 points ±or the methanol combustion reaction 2 CH 3 OH( ) + 3 O 2 (g) -→ 2 CO 2 (g) + 4 H 2 O(g) estimate the amount oF P Δ V work done and tell whether the work was done on or by the system. Assume a temperature oF 27 C. 1. 7.5 kJ, work done on the system 2. 7.5 kJ, work done by the system correct 3. 2.5 kJ, work done by the system 4. 2.5 kJ, work done on the system 5. No work is done in this reaction. Explanation: T = 27 C + 273 = 300 K Considering only moles oF gas, Δ n = n f - n i = (2 + 4) - 3 = 3 . w = - Δ nRT = - (3 mol) (8 . 314 J / mol · K) (300 K) = - 7500 J = - 7 . 5 kJ The system expands because Δ n is positive, so the system does the work on the surround- ings. Also, when w is negative, work is done by the system. 003 10.0 points Heat ²ow is considered positive when heat ²ows (into, out oF) a system; work is consid- ered positive when work is done (by, on) a system. 1. out oF; by 2. into; by 3. into; on correct 4. out oF; on Explanation: Heat ²ow q is considered positive when heat ²ows into a system. Work w is considered positive when work is done on a system. 004 10.0 points Which one oF the Following statements is ±ALSE? ±or a reaction carried out at con- stant pressure in an open container 1. the heat absorbed by the system can be called Δ H . 2. the work done on the system can be set equal to - P Δ V . 3. the work done on the system can be set equal to - V Δ P . correct 4. the work done on the system can be set
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kapur (rk7259) – Homework 11 – Lyon – (52380) 2 equal to - n ) RT , where Δ n is the num- ber of moles of gaseous products minus the number of moles of gaseous reactants. Explanation:
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This note was uploaded on 01/30/2010 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas.

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Hwk 11 Solutions - kapur (rk7259) Homework 11 Lyon (52380)...

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