Download Free Energy Equations

BIOENERGETICS EQUATIONS
FREE ENERGY
∆G = ∆H - T∆S
Gibbs Free Energy
useful work
entropy
disorder ("lost energy")
enthalpy
heat
When adding reactions, add ∆Go's.
When writing a reaction in the other direction, change sign on ∆Go'.
1 kcal = 1 Cal = 4.184 kJ
The general equation for Gibbs Free Energy is:
∆G
=
∆Go' + RT ln Q
[products] j
R = 1.987 X 10-3 kcal/mol. K
Q =
T = temperature in kelvins
[reactants] i
(But be careful when H+ is in the reaction.)
∆Go' comes from measuring the equilibrium constant.
at equilibrium
∆G = 0
so
∆Go' = -RT ln Keq
Keq =
or
Free Energy for Oxidation-Reduction
∆G
= - nFE
n is the number of moles of electrons transferred
.
F is the Faraday constant (23.06 kcal/V mol)
E is the electrical potential (Voltage)
e
-∆Go'
RT