EQUILIBRIUM Study Sheet Part I

1. Write the K expression for the following:

(a) 2NaHCO3(s) n Na2CO3(s) + CO2(g) + H2O (g)

(b) 2NO2 (g) + 7H2 (g) n 2NH3(g) + 4H2O (l)

NOTE: for the following equations, all are gases unless noted

2. If the equilibrium constant Kp for reaction 1(b) above is 1.5 at 25oC, what is the Kc?

3. The equilibrium constant, Kc, for the reaction 2HCl n H2 + Cl2 is 4.17 x 10-34 at 25oC.

(a) What is the equilibrium constant for H2 + Cl2 n 2HCl?

(b) What is the equilibrium constant when 1 mole of HCl decomposes?

4. For the reaction at 700oC: 2H2 + S2 n 2H2S, analysis shows that there are 2.50 moles of H2, 1.35 x 10-5 mole of S2, and 8.70 moles of H2S present in a 12.0 L flask. What is the Kc? What is the Kp?

5. What is Kp at 1273oC for the reaction: 2CO + O2 n 2CO2 if Kc is 2.24 x 1022?

6. The Kp value for the reaction: 2SO3 n 2SO2 + O2 is 1.8 x 10-5 at 350oC.

(a) What is the value of Kc?

(b) If the pressure of SO2 is 1.52 atm and O2 is 0.78 atm, what is the pressure of SO3 at equilibrium?

7. At equilibrium, a vessel contains 0.25 M ammonia, 0.11 M nitrogen and 1.91 M hydrogen, what is Kc for the reaction: N2 + 3H2 n 2NH3? If the temperature is 150oC, what is Kp?

8. Using the equation from #7, the equilibrium constant, Kc, at 720oC is 2.37 x 10-3. In a certain experiment, the equilibrium concentration of nitrogen was 0.683 M and ammonia was 1.05 M. What is the concentration of hydrogen? What is Kp?

9. Using the information from Kp and temperature values from ?7 and ?8, find DH using van't Hoff's equation.

9. At 1130oC the equilibrium constant, Kc, for the reaction: 2H2 + S2 n 2H2S is 2.25 x 10-4. If [H2S] = 4.84 x 10-3 M and [H2] = 1.5 x 10-3 M, what is [S2]?

10. At 1000K, a sample of pure NO2decomposes: 2NO2 n 2NO + O2. The Kp is 158. Analysis shows that the equilibrium partial pressure of oxygen is 0.25 atm. What is the equilibrium partial pressures of NO and NO2 (you actually know NO—think!)? Calculate DG.

11. At a certain temperature, the following reactions have these Kc values:

S(s) + O2 D SO2 Kc = 4.2 x 1052

2S (s) + 3O2 D 2SO3 Kc = 9.8 x 10128

Find the Kc value for 2SO2 + O2 D 2SO3 at this temperature.