TUTORIAL 2 CHEMICAL EQUILIBRIUM

CHM 096 TUTORIAL 2
(Chemical Equilibrium)

1. Write the equilibrium constant expression, Kc, for each of the following reactions:
a) 2NO(g) + O2(g) ⇄ 2NO2(g)
b) The decomposition of solid potassium chlorate to solid potassium chloride and oxygen gas.
c) 4HCl(g) + O2(g) ⇄ 2H2O(g) + 2Cl2(g)
d) 2NO2(g) + 7H2(g) ⇄ 4H2O(l) + 2NH3(g)
e) H2O(g) + C(s) ⇄ CO(g) + H2(g)
f) The reduction of solid copper (II) oxide with hydrogen gas to produce copper metal and water at 500oC.

2. The equilibrium constant Kc for the reaction: 2HCl(g) ⇄ H2(g) + Cl2(g) is 0.0213 at 400 oC. If 20.0 moles of HCl(g) are heated at 400 oC, what amounts of HCl(g), H2(g) and Cl2(g) would be present in the equilibrium mixture? (H2 = Cl2 = 2.26 moles; HCl = 15.48 moles)

3. The equilibrium constant Kc for the reaction: 2CO(g) + O2(g) ⇄ 2CO2(g) is 2.24 x 1022 at 1273oC. Calculate the Kp for the reaction at the same temperature.
(1.76 x 1020)
4. A 2.50 mole sample of NOCl was placed in a 1.50-L container at 400oC. When equilibrium has established, it was found that 28% NOCl has dissociated according to the reaction:
2NOCl(g) ⇄ 2NO(g) + Cl2(g) Calculate the equilibrium constant Kc (0.0356)

5. Consider the reaction: H2(g) + CO2(g) ⇄ H2O(g) + CO(g) 0.80 mole of H2 and 0.80 mole of CO2 are placed in a 5-dm3 container at 1650 oC. At equilibrium, 0.25 mole of CO was found in the equilibrium mixture. Calculate the equilibrium constant Kc. (0.2)
6. For the reaction: 2NO2(g) ⇄ N2O4(g) , the value of Kc is 0.5 at 450oC. A 1-L container consists of 2.0 moles NO2 and 2.0 mole N2O4 450oC. Is the mixture at equilibrium? If not, in which direction must the reaction proceed to reach equilibrium?

7. Kc and Kc’ are the equilibrium constants for reactions I and II respectively. I. 3H2(g) + N2(g) ⇄ 2NH3(g) II. ³/2 H2(g) + ½ N2(g) ⇄ NH3(g) a) Write the equilibrium constant expressions for Kc and for Kc’. Derive a