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ps2solutions - Chemistry 4511 Problem Set 2 1. For the...

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Chemistry 4511 Problem Set 2 1. For the reaction 2CO 2 Æ 2CO + O 2 a. If there are initially 0.534 moles of CO 2 and 0.42 moles of CO are generated at some time, demonstrate that ξ is the same with respect to each component. b. Once the reaction goes to completion, there is a H value measured at T = 1000 K. Calculate the expected value for H two ways and compare the values (use heats of formation and bond enthalpies and adjust the H value away from standard T using C P ,m(T)) a. ξ = n i / ν i i ν i n i C O 2 -2 -0.42 CO +2 +0.42 O 2 +1 +0.21 ξ CO2 = -0.42/-2 = 0.21 ξ CO = 0.42/2 = 0.21 ξ O2 = 0.21/1 = 0.21 b. H o = Σ∆ f H o prod Σ∆ f H o react = 2(-110.53)+0-2(-393.51) = 565.96 kJ/mol H o = Σ∆ H broken Σ∆ H formed = 2(531) – 497 = 565 kJ/mol C P,m = d + eT + fT -2 d = 2(28.41) + 29.96 – 2(44.22) = -1.44 J K -1 mol -1 e(x 10 3 ) = 2(4.1) + 4.18 – 2(8.79) = -5.2 Æ -5.2 x 10 -3 J K -2 mol -1 f(x 10 4 ) = 2(-4.6) + (-16.7) – 2(-86.2) = 146.5 1.465 x 10 6 J K mol -1 C P,m = -1.44 – 5.2 x 10 -3 T + 1.465 x 10 6 T -2 + = = ∆∆ 1 2 2 1 2 2 1 2 , 1 1 ) ( 2 ) ( ) ( 2 1 T T f T T e T T d dT C T H T T m P + = ∆∆ 15 . 298 1 1000 1 10 465 . 1 ) 15 . 298 1000 ( 2 10 2 . 5 ) 15 . 298 1000 ( 44 . 1 ) ( 6 2 2 3 x x T H 1 69 ) ( = ∆∆ Jmol T H so H 1000 = H o + ∆∆ H H 1000 = 565.96 + 0.069 = 566.029 kJ/mol for formation constants H 1000 = 565 + 0.069 = 565.069 kJ/mol for bond enthalpies We can see that the T dependence is not significant compared to the process, and this is typically the case. Also, we see that the two ways of deriving
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ps2solutions - Chemistry 4511 Problem Set 2 1. For the...

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