E115_Problem_Set_25

# E115_Problem_Set_25 - n CO 2 n CO n H 2 O and n H 2 in...

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e 115 Engineering Thermodynamics Fall 2009 University of California Problem set 25 Due: Monday, November 23 th , in lecture 1) (30 points) A CO 2 –CO–H 2 –H 2 O gas mixture at a total pressure of 1 atm exerts an oxygen partial pressure of 10 -7 atm at 1600°C. We wish to find the ratio in which CO 2 and H 2 were mixed to produce this value of P O 2 . The following information is provided: C + 1 2 O 2 = CO Δ G° = 111, 700 87.65 T J mole -1 C + O 2 = CO 2 Δ G° = 394,100 0.84 T J mole -1 H 2 + 1 2 O 2 = H 2 O Δ G° = 141, 940 J mole -1 Let the initial number of moles of CO 2 be a and the initial number of moles of H 2 be 1. Then the required ratio is a /1= a . Let x be the number of moles of CO 2 that react and let y be the number of moles of H 2 that react. a) Write down the two reactions that occur. One should involve CO and CO 2 and the other should involve H 2 and H 2 O. Label the CO–CO 2 reaction I and the H 2 –H 2 O reaction II. (2 points) b) Write expressions for
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Unformatted text preview: n CO 2 , n CO , n H 2 O , and n H 2 in terms of a , x , and y . (4 points) c) Write expressions for n total , X CO 2 , X CO , X H 2 O , and X H 2 involving a , x , and y . (4 points) d) x is approximately equal to y . Explain why x and y are not equal but very close in value. (2 points) e) Write expressions for K P I and K P II in terms of gas pressures. (4 points) f) Write expressions for K P I and K P II in terms of mole fractions, where possible. (4 points) g) At the temperature of interest, what are K P I and K P II ? You should be able to give a numerical value. (2 points) h) In light of the above steps, what is a ? (3 points) i) What oxygen partial pressure is exerted by the equilibrium gas mixture produced by mixing CO 2 and H 2 in the ratio 3:1? (5 points)...
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## This note was uploaded on 02/12/2011 for the course E 115 taught by Professor Staff during the Fall '08 term at Berkeley.

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