Standard Change in Free Energy

by Soaring Crane
Tags: energy, free, standard
Soaring Crane
Soaring Crane is offline
Apr11-06, 11:29 AM
P: 483
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
Soaring Crane is offline
Apr12-06, 09:53 PM
P: 483
Are my answers valid?


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