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Spontaneous Reactions
Equilibrium Constant
ICE Diagrams
Reaction Quotient
Le Chatelier's Principle
100
If a reaction is spontaneous in the forward direction, it is __________________ favoured.
Product favoured!
100
What phases are included in the equilibrium expression?
Gaseous and aqueous!
100

4A (g) + 3B (g) <---> 5C (g)
Initially, 10 mol A and 15 mol B are put in a 5L flask. What are the initial concentrations of A, B, and C?

2 M, 3 M, 0 M.

100
What does the reaction quotient determine?
Which way the equilibrium reaction is running!
100
What does Le Chatelier's Principle determine?
If you disturb a system at equilibrium, it will shift so as to minimize the disturbance.
200
Define entropy!
A measure of disorder in a system!
200

When is Keq reactant favoured?

When it is less than 1/1000!

200

What does the change from initial to final concentration represent?

The amount of reactant or product that reacts as we go to equilibrium.

200
What Q = Keq, which way does the system run?
It's at equilibrium!
200
Name 4 factors that will shift a system at equilibrium!
Concentration, temperature, volume, pressure!
300
Define dynamic equilibrium!
The rate of the forward reaction is equal to the rate of the reverse reaction
300

4A (g) + 2B (g) <---> 3C (g) What is the equilibrium expression?

Keq =             [C]3 
                -------------
                  [A]4 [B]2

300

P2 + 3H2  <--->  2PH3 
Initially, 4 mol P2 and 8 mol H2 are put in a 2L flask. Which way will the reaction run?

To the right!

Initially we have omly reactants, so it will proceed to the right until we reach equilibrium.

300
How is the reaction quotient calculated?
Same as Keq but use initial concentrations!
300
CO2 + H2O <---> H2CO3 If we dump in some H2CO3, what will happen to the concentration of all 3 species?
All three will increase!
400

List 4 characteristics of chemical equilibrium!

Must be a closed system, must be reversible, must have some of all species present at equilibrium, must involve a chemical change!

400

3.5A (g) + 4B (aq) + C(l) <---> 8D (s) + 1.5E (s) + 6F (l)
What is the equilibrium expression?

Keq =       1
          -----------
          [A]3.5 [B]4

400

H2 + F2  <--->  2HF
Initially, 10 mol H2 and 6 mol F2 are in a 2L flask. At equilibrium, 5 mol HF are present. Draw and fill in the ICE diagram on the board.

   H2    +    F2    <--->    2HF

I  5M         3M                  0

C  -x          -x                 +2x

E  5-x        3-x                 2.5M    so x = 1.25M

    3.75M    1.75M             2.5M


Keq =         (2.5)2

              -------------  =  0.9524

               (3.75)(1.75)

400
A + B <---> C + D A 32 L flask has 16 mol of A, B, C, and D. If Keq is 58.5, determine which way the reaction is running!
To the right!
400
What happens to a system at equilibrium when you add a catalyst?
Both the forward and reverse reactions will speed up so there will be no change overall!
500
In general, spontaneous processes occur because of a desire to become energetically _________________ and more __________________
More stable and more disordered!
500

Does the equilibrium constant for the reaction
Br2(l)   <===>  Br2(g)
increase or decrease as temperature increases?

Increases!

As  the temperature increases more of the liquid bromine (reactant) becomes a gas, hence increasing the product side.

500

N2  +  3H2  <--->  2NH3 
Initially, 12 mol NH3 are put in a 2L flask. At equilibrium, the concentration of N2 is 1 M. What is the Keq?

   N2    +    3H2   <--->   2NH3 
I   0             0                  6M
C  +x         +3X                -2x
E   1M   so x = 1
      1            3                (6 - 2 = 4)

Keq  =           4
               ---------  =  4/3 = 1.33
                 (1)(3)

500
A + 2B <---> 4C + D Initially, 4 mol of A, B, C, and D are put in a 2L flask. If Keq is 4, which way is the reaction running?
It's at equilibrium!
500
5A (g) + 9D (l) <---> 6E (aq) + 3G (g) If we increase the volume, which way will the reaction shift?
Left!