1. EQUILIBRIUM LAW

2. These constant values indicate the equilibrium law.
When you use concentration data to FIND OUT whether you can get a constant value by manipulating it, you are finding Q, the reaction quotient. E.g. 2HI  H2 + I2
These are all Q values.
These constant values indicate
the equilibrium law.
Trial Number
[H2][I2] /[HI]
[H2][I2] /[HI]2
[H2][I2] /2[HI] 1
3.24×104
1.83×102
1.62×104 2
3.02×104
1.51×104 3
2.50×104
1.85×102
1.25×104 4
0.65×104
0.32×104

3. K is the equilibrium constant at a given temperature (no units)
General equation:
K =
Where [X] means molar
concentration of X
m, n are coefficients from
balanced equation

4. e.g. For 2NO(g) + O2(g)  2NO2(g) [NO] 2[O2]
K = [NO2]2
[NO] 2[O2]
Write the equilibrium law for
a) 2H2 + O2  2H2O
b) 3H2 + N2  2NH3
a) K = [H2O]2 b) K = [NH3]2
[H2]2[O2 ] [H2]3[N2]

5. If the concentrations for the substances in the equilibrium 3H2 + N2  2NH3 are [H2] = mol/L, [N2] = mol/L, and [NH3] = mol/L at 300 K, what is the equilibrium constant for that temperature? K = [NH3]2 [H2]3[N2] K = 3.36 What does a large K indicate about the position of the equilibrium? Small K?

6. If the equilibrium constant for the reaction 2H2 + O2  2H2O at 600C is K=7.32×105, and concentra-tions of these substances in a closed system are [H2] = 5.81×103 mol/L, [O2] = 9.16×104 mol/L, and [H2O] = 7.33×106 mol/L, is the system at equilibrium? *Find Q and compare to K Q = [H2O]2 [H2]2[O2 ] Q = 1.74×103  K not at eqbm.

7. In what direction must the water system shift to attain equilibrium
In what direction must the water system shift to attain equilibrium? The position of the equilibrium must shift toward reactants, so that the value of Q gets smaller.