Equilibrium Constant Expression

CHM 096

TUTORIAL 2 (Chemical Equilibrium)

Jan 2013

1.

Write the equilibrium constant expression, Kc, for each of the following reactions: a) b) c) d) e) f) 2NO(g) + O2(g) ⇄ 2NO2(g) The decomposition of solid potassium chlorate to solid potassium chloride and oxygen gas. 4HCl(g) + O2(g) ⇄ 2H2O(g) + 2Cl2(g) 2NO2(g) + 7H2(g) ⇄ 4H2O(l) + 2NH3(g) H2O(g) + C(s) ⇄ CO(g) + H2(g) The reduction of solid copper (II) oxide with hydrogen gas to produce copper metal and water at o 500 C. 2H2(g) + O2(g) ⇄ 2H2O(g) are 2.50, 1.35 x 10‒5 and 8.70 moles respectively in a 12-L flask. Calculate the equilibrium constant 7 Kc. (1.08 x 10 )

2.

The number of moles of H2, O2, and H2O present at equilibrium for the reaction:

3.

The equilibrium constant Kc for the reaction: 2HCl(g) ⇄ H2(g) + Cl2(g) is 0.0213 at 400 C. If 20.0 o moles of HCl(g) are heated at 400 C, 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) o 4.

The equilibrium constant Kc for the reaction: 2CO(g) + O2(g) ⇄ 2CO2(g) is 2.24 x 10 at 1273 C. Calculate the Kp for the reaction at the same temperature. 20 (1.76 x 10 )
22 o

5.

A 2.50 mole sample of NOCl was placed in a 1.50-L container at 400 C. 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)

o

6.

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-dm container at 1650 C. At equilibrium, 0.25 mole of CO was found in the equilibrium mixture. Calculate the equilibrium constant K c. (0.2)
3 o

7.

For the reaction:

2NO2(g) ⇄ N2O4(g) , the value of Kc is 0.5 at 450 C. o o

A 1-L container consists of 2.0 moles NO2 and 2.0 mole N2O4 450 C. Is the mixture at equilibrium? If not, in which direction must the reaction proceed to reach equilibrium? 8. Kc and Kc are