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Standard Change in Free Energy

by Soaring Crane
Tags: energy, free, standard
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Soaring Crane
Apr11-06, 11:29 AM
P: 484
Are my final values correct?

1. Determine the free energy change associated with the formation of methanol from carbon monoxide and hydrogen gas if the partial pressure of CO is 1.0700 atm, H2 is 2.2800 atm, and CH3OH is 0.0600 atm at 298K. The standard free energy of formation for methanol is - 24.70 kJ. Give your answer in kilojoules.

CO (g) + 2H2 (g) --> CH3OH (g)

deltaG* = -24.70 kJ = -24,700 J

deltaG = G* + RTlnQ

Q = [(CH3O)]/[(CO)*(H2)^2] = [0.06 atm]/[(2.28 atm)^2*(1.07 atm)]
= 0.010786928

delta G = -24,700 J + (298 K)(8.314)ln(0.010786928)
= -35921.965 J
= -35.92 kJ

2. The compound AB can be formed from A and B according to the following reaction:A2 (g) + B2 (g) --> 2 AB (g) If the free energy of formation for AB is 8.66 kJ/mol, what is the equilibrium constant for the reaction at 181C? Give your answer to four decimal places.

deltaG* = 2 mol(8.66 kJ/mol) = 17.32 kJ = 17,320 J

deltaG* = RTlnK

K = e^-(G/RT)
= e^-(17,320 J/(8.314 J *454.15 K))
= e^-(4.5871)
= 0.10182 = 0.1018 ???

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Soaring Crane
Apr12-06, 09:53 PM
P: 484
Are my answers valid?


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