1. Standard Gibbs Free Energy
Review
Standard Gibbs Free Energy
Go =
Ho
- TSo
Go < 0
spontaneous
Go = kJ/mol
Go > 0
non-spontaneous
Go = kJ/mol
Go = 0
equilibrium
Go = kJ/mol
glucose
+ phosphate 
glucose-6-phosphate
+ H2O
ATP
+ H2O 
ADP
+ phosphate
glucose
+ ATP
 ADP +
glucose-6-phosphate

2. Non-standard conditions
reaction quotient
= [products] m
Q =
initial
[reactants] n
initial
K =
equilibrium constant
= [products] m
equilibrium
[reactants]
equilibrium n
G =
- RT
ln ( ) K /Q
K > Q
G < 0
spontaneous
G > 0
K < Q
non-spontaneous
K = Q
G = 0
equilibrium

3. Go G = - RT ln(K) o G = - RT ln(K/Q) Standard Free Energy
Impose Standard conditions:
[reactants]initial
= 1(M or atm)
= [products]initial
Q = 1
G =
- RT ln(K) o
Standard Free Energy

4. Non-Standard Conditions
G =
Go
+ RT ln Q
G = - RT ln (K/Q)
Go = - RT ln K
ln (a/b) =
ln a
- ln b
G = - RT ln (K/Q) =
-RT ln K
+ RT ln Q

5. Go = - RT ln(K) G = - RT ln ( ) K /Q G < [products] glucose
+ phosphate 
glucose-6-phosphate
+ H2O
standard conditions
non-spontaneous
Go = kJ/mol
= -RT ln K
K =
1.2 x 10-3
-RT
G =
- RT
ln ( ) K /Q G
< Q
< K
<
1.2 x 10-3
non-standard conditions
[products]
[reactants]
initial
Q =
start with no product
spontaneous

6. Non-Standard Conditions
G =
Go
+ RT ln Q
2NO2 (g) N2O4 (g)
Initially
[NO2] = 0.3 M
[N2O4] = 0.5 M
Will more products or reactants be formed?
Q =
0.5 /
0.32
= 5.6

7. Non-Standard Conditions
G =
Go
+ RT ln Q
2NO2 (g) N2O4 (g)
Initially
[NO2] = 0.3 M
[N2O4] = 0.5 M
Gorxn = Gof products - Gof reactants =
2(51.3) =
- 4.8 kJ/mol
Grxn=
-4.8 +
(8.314 x 10-3)(298)
ln 5.6
= -0.5 kJ/mol
More N2O4 will be formed

8. Le Chatelier’s Principle
G = -RT ln (K/Q)  A +B C
K =
[C]e
Q =
[C]i
[A]e[B]e
[A]i[B]i
Le Chatelier’s Principle
Add A
decrease Q
K/Q
> 1
Add B G
>
< 0
Remove A
increase Q
K/Q
< 1

9. Temperature dependence of K
exothermic reaction
heat =
product
at low T
favor forward reaction
at high T
favor reaction
reverse
endothermic reaction
heat =
reactant
at low T
favor reaction
reverse
at high T
favor reaction
forward

10. Temperature dependence of K
Go = -RT ln K
Go =  Ho - TSo
-RT ln K =
 Ho - TSo
- Ho R 1 T
+ So R
ln K = m x b
ln K y
Ho < 0
1/T
increase T
decrease K T

11. Temperature dependence of K
Go = -RT ln K
Go =  Ho - TSo
-RT ln K =  Ho - TSo
- Ho R 1 T
ln K =
+ So R -
ln K y m x b
endothermic
H > 0
1/T
increase T
increase K T