Chemistry 12 Equilibrium Review
-Be able to list what is true about a system at equilibrium and recognize when a system is at equilibrium
- Be able to write an equilibrium constant expression and know what to do about solids and liquids
- be able to calculate a Kc value given equilibrium concentrations
- be able to interpret whether products or reactants are favoured at equilibrium by looking at the value
of the Kc
-Be able to do an ice table problem
-Use LeChataliers principle to predict the shift of a system at equilibrium in response to a stress and
explain why it would happen
- Use Qc to tell if a system is at equilibrium and whether the system has to go to products or reactants
to reach equilibrium.
-explain what is meant by equilibrium in a solution and set up an appropriate ionic equation and Ksp
equation
Be able to calculate the {ion} in a saturated solution.
1.
2.
Chemistry 12 Equilibrium Review
3.
4.
One mole of very cold, colorless N2O4 (g) is placed into a 1.0L glass container of room
temperature. The reaction:
N2O4 (g)
⇄
2 N02 (g)
H= +58 KJ
(colorless)
(brown)
proceeds to equilibrium. The concentration of each gas is measured as a function of time.
Time (s)
[N2O4] (M)
[N02] (M)
a)
0
1.0
0.0
5
0.83
0.34
10
0.81
0.38
15
0.80
0.40
20
0.80
0.40
25
0.80
0.40
At what time was equilbirum established? B) What would you see at equilibrium?
5.
State the direction in which each of the following equilibrium systems would be shifted upon
the application of the following stress listed beside the equation.
1. 2 SO2 (g) + O2 (g)
⇄
2. C (s) + CO2 (g) + energy
3. N2O4 (g)
⇄
4. CO (g) + H2O (g)
2 SO3 (g) + energy
decrease temperature
⇄
increase temperature
2 CO (g)
2 NO2 (g)
increase total pressure
⇄
decrease total pressure
CO2 (g) + H2 (g)
Chemistry 12 Equilibrium Review
6.
⇄
2SO3(g)
2SO2(g)
+ O2(g)
+
215 KJ
Describe four ways of increasing the yield of for the reaction above.
7.
Keq= 798 at 25oC for the reaction: 2SO2 (g) + O2 (g) ⇄ 2SO3 (g).
In a particular mixture at equilibrium, [SO2]= 4.20 M and [SO3]=11.0M. Calculate the
equilibrium [O2] in this mixture at 25oC.
8.
Consider the following equilibrium:
2SO2 (g) + O2 (g) ⇄ 2SO3 (g)
When 0.600 moles of SO2 and 0.600 moles of O2 are placed into a 1.00 litre container
and allowed to reach equilibrium, the equilibrium [SO3] is to be 0.250 M. Calculate the
Keq value.
9. Suppose you are studying a reaction A + B C. All reactants and products are gases. If the
Keq is 25 and you happen to meaure some concentration values and discover that [A] = 2M, [B]=
6M and [C] = 12M. Is the system at equilibrium and if not, which way does it have to go to get
there?