1. Write the equilibrium constant expression for the following:
CS2(g) + 4 H2(g) ⇌ CH4(g) + 2 H2S(g) Kp =
2. Calculate the value of Kp for the above reaction if the equilibrium pressures for each of the
components are as follows:
஼ௌమ = 0.500 , ுమ = 0.100 , ஼ுర = 1.00 , ுమௌ = 0.800
3. Given the above equilibrium reaction, predict in which direction the equilibrium will shift if the
pressure of the vessel is decreased. Explain in 2-3 sentences why
4. If the Kp of your reaction = 0.00274, calculate what Kc should be using the equation Kp = Kc(RT)Δn
5. For the reaction: A2(g) + B(g) ⇌ 2C(g) it is found that by adding 1.5 moles of C to a 1.0 L
container, an equilibrium is established in which 0.30 moles of B are produced.
a) What is [A] at equilibrium?
b) What is [B] at equilibrium?
c) What is [C] at equilibrium?
d) Write the expression for the equilibrium constant, Keq
e) Calculate the value for the equilibrium constant
6. Consider the reaction 2NO2(g) ⇌ N2O4(g) to be at equilibrium with
[NO2(g)] = 1.60 M, [N2O4] = 0.20 M, and Kc = 0.078.
1. Predict qualitatively what will happen to this reaction if more NO2 is added so that
[NO2(g)] = 2.00 M?
2. Predict qualitatively what will happen to this reaction if instead NO2 is removed so that
[NO2(g)] = 1.00 M?
7. Calculate the values for Qc for these two experiments.
(a) [NO2(g)] = 2.00 M and [N2O4] = 0.20 M: Qc =
(b) [NO2(g)] = 1.00 M and [N2O4] = 0.20 M: Qc =
8. What in general happens to a reaction if
(a) Qc Kc
9. A mixture of H2 and I2 is allowed to react at 448°C. When equilibrium is established, the
concentrations of the participants are found to be:
[H2] = 0.46 M, [I2] = 0.39 M and [HI] = 3.0 M.
The equation is: H2(g) + I2(g) ⇌ 2HI(g)
Calculate the value of Keq at 448°C.
10. CO(g) + H2O(g) ⇌ CO2(g) + H2(g)
At 900 K, Kc = 1.56 for this reaction. A sample of water gas flowing over coal at 900 K contains a
1:1 mole ratio of CO(g) and H2(g), as well as 0.250 mol L–1 H2O(g). This sample is placed in a
sealed container at 900 K and allowed to come to equilibrium, at which
point it contains 0.070 mol L–1 CO2(g). What was the initial concentration of CO(g) and H2(g) in
the sample?
11. At 700 °C, hydrogen and iodine react according to the following equation.
H2(g) + I2(g) ⇌ 2HI(g) Kc = 49.0
Hydrogen also reacts with sulfur at 700 °C:
2H2(g) + S2(g) ⇌ 2H2S(g) Kc = 1.075 × 108
Calculate Kc for the following overall equilibrium reaction at 700 °C.
2I2(g) + 2H2S(g) ⇌ S2(g) + 4HI(g) Kc = ?
12. The KC for the reaction: PCl5(g) ⇌ PCl3(g) + Cl2(g) at 250°C is found to be 0.042. In an equilibrium
mixture of these species, it is found that [PCl5] = 0.012 M, and [Cl2] = 0.049 M. What is the
equilibrium [PCl3] at 250 °C?
13. At a certain temperature, the reaction: CO(g) + 2H2(g) ⇌ CH3OH(g) has a Keq = 0.500. If a reaction
mixture at equilibrium contains 0.210 M CO and 0.100 M H2, what is the equilibrium [CH3OH]?
14. Given the equilibrium equation: H2(g) + I2(g) ⇌ 2HI(g) at 448°C, Keq = 50.
If 3.0 mol of HI, 2.0 mol of H2, and 1.5 mol of I2 are placed in a 1.0 L container at 448°C, in which
direction will the reaction go? Towards the left or towards the right?
15. Given the equilibrium equation: H2(g) + I2(g) ⇌ 2HI(g) at 448°C, Keq = 50. If 5.0 mol of HI, 0.7071
mol of H2, and 0.7071 mol of I2 are placed in a 1.0 L container at 448°C, will a reaction occur?
16. Given the reaction: 4HCl(g) + O2(g) ⇌ 2H2O(g) + 2Cl2(g) ΔH = -113 kJ
How will the value of the equilibrium constant Keq at 550 oC compare with its value at 450 oC?
17. Using the principles postulated by Le Châtelier, predict which direction (left, right, or no change)
the given reaction will go if the following occurs:
4 NH3(g) + 5 O2(g) ⇌ 4 NO(g) + 6 H2O(g) ΔHrxn = -905.5 kJ/mole
a. Nitrogen monoxide is added to the vessel:
b. The pressure in the vessel is increased:
c. The reaction is cooled:
d. Carbon dioxide gas is pumped into the reaction vessel: