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Author Topic: Standard free-energy change and equilibrium constant  (Read 556 times)

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Iamyourfather

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Standard free-energy change and equilibrium constant
« on: November 26, 2012, 01:23:30 AM »

Are my answers correct?

What is the standard free-energy change (ΔG'°) for the conversion of pyruvate to lactate?

ΔG’° = -nFDE°'       ΔE’°   = -0.19 V - (-0.32 V) = + 0.13 V
NADH is a two electron donor, therefore n = 2.
ΔG° = - 2 x 96,500 J mol-1 V-1 x 0.13 V = -25090 J mol-1 = -25.09 kJ mol-1

e) What is the equilibrium constant (K' eq) for this reaction?

Constants: R = 8.31 J mol-1 K-1. F = 96,500 J mol-1 V-1
ΔG’0 = -RT ln K
ΔG’0 = ΔG' = -RT In K/Γ
Γ = 1 M x 1 M/1 M x 1 M x 1 M = 1 M-1
   ΔG’0
-  ---- = ln K
   RT
K’eq = e-ΔG’0/RT = e- -25090 Jmol-1 / 8.31 J mol-1 K-1 x 298 K = e 25090/8.31 x 298 = e 25090/2476.38 = e10.13 = 25084.4 M-1
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Babcock_Hall

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Re: Standard free-energy change and equilibrium constant
« Reply #1 on: November 26, 2012, 10:06:39 AM »

This appears to be correct.
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