problem solving

Equilibrium: Shift with Le Chatelier

 1) For the reaction below, which change would cause the equilibrium to shift to

the right?

CH4(g) + 2H2S(g) ↔ CS2(g) + 4H2(g)

(a) Decrease the concentration of dihydrogen sulfide.

(b) Increase the pressure on the system.

(c) Increase the temperature of the system.

(d) Increase the concentration of carbon disulfide.

(e) Decrease the concentration of methane.

2) What would happen to the position of the equilibrium when the following

changes are made to the equilibrium system below?

2SO3(g) ↔ 2SO2(g) + O2(g)

(a) Sulfur dioxide is added to the system.

(b) Sulfur trioxide is removed from the system.

(c) Oxygen is added to the system.

3) What would happen to the position of the equilibrium when the following

changes are made to the reaction below?

2HgO(s) ↔ Hg(l) + O2(g)

(a) HgO is added to the system.

(b) The pressure on the system increases.

4) When the volume of the following mixture of gases is increased, what will be

the effect on the equilibrium position?

4HCl(g) + O2(g) ↔ 2H2O(g) + 2Cl2(g)

5) Predict the effect of decreasing the volume of the container for each equilibrium.

(a) 2H2O(g) + N2(g) ↔ 2H2(g) + 2NO(g)

(b) SiO2(s) + 4HF(g) ↔ SiF4(g) + 2H2O(g)

(c) CO(g) + H2(g) ↔ C(s) + H2O(g)

6) Predict the effect of decreasing the temperature on the position of the

following equilibria.

(a) H2(g) + Cl2(g) ↔ 2HCl(g) + 49.7 kJ

(b) 2NH3(g) ↔ N2(g) + 3H2(g) Δ H = 37.2 kJ

(c) CO(g) + H2O(g) ↔ CO2(g) + H2(g) Δ H = -27.6 kJ

Calculations with Q and K

Consider the following reaction.

2 NO2(g) <--> N2O4(g)

1.    Write the equilibrium expression for this reaction.

2.    Calculate the equilibrium constant given the equilibrium conditions at 320 K where:

3.    PNO2 = 0.10 atm

4.    PN2O4 = 0.018 atm

5.    Given the following initial conditions, predict the direction of the reaction.

NO2  (atm)           N2O4(atm)

0.10                      0.10

0.010                     0.010

1.0                          2.0

2.0                          7.0

0.01                       1.8x10-4

0.5                          0.5

4.    Given the initial, non-equilibrium, conditions. Calculate the equilibrium pressure of NO2 and N2O4.

1.    PNO2 = 0.20 atm; PN2O4 = 0.00 atm

2.    PNO2 = 0.00 atm; PN2O4= 0.20 atm

3.    PNO2 = 0.20 atm; PN2O4 = 0.20 atm