text Calculate Gº, Hº, and Sº at 25ºC for the reaction below in the indicated un
ID: 524808 • Letter: T
Question
text
Calculate Gº, Hº, and Sº at 25ºC for the reaction below in the indicated units.
[Use thermodynamic data from the lecture note manual appendix or the class handout. The class handout is more extensive and may contain data not in the lecture note manual]
3 NH (l) + 4 O (g) 6 NO (g) + 6 HO (l)
Note: This reaction involves ozone, O3, not oxygen gas, O2.
Gº = -2034.356 kJ
Hº = kJ
Sº = J/K
My calculated delta H and delta S were off, but somehow they gave me the right Free energy for the problem. Not sure what I'm messing up on.
Explanation / Answer
Hº = Hº f(Products) - Hº f (Reactants)
= 6 Hºf(NO) + 6 Hºf(H2O) - 3 Hºf(N2H4) - 4 Hºf(O3)
= 6(90.25)+6(-285.8)-3(50.63)-4(142.7)
= - 1896 kJ
Sº = Sº f(Products) - Sº f (Reactants)
= 6 Sºf(NO) + 6 SHºf(H2O) - 3 Sºf(N2H4) - 4 Sºf(O3)
= 6(210.6)+6(69.91)-3(121.2)-4(238.8)
= + 364.26 J/K
Gº = Gº f(Products) - GHº f (Reactants)
= 6 Gºf(NO) + 6 Gºf(H2O) - 3 Gºf(N2H4) - 4 Gºf(O3)
= 6(86.57)+6(-237.2)-3(149.2)-4(163.2)
= - 2004.18 kJ
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