Calculating Equilibrium Constants:

1. Calculating Equilibrium Constants: The actual value of Keq is found experimentally. The individual concentrations of all the reactants is calculated, and the temperature recorded. This is because the value of Keq will change with temperature. What can Keq tell you? Which direction is favored.

2. Take the equiibrium: A(g) B(g) • If the value of Keq is one then ….reaction is at equilibrium [A] = [B] • If the value of Keq is less than one ……reactants are favored A(g) B(g) • If the value of Keq is greater than one then ………products are favored A(g) B(g)

3. Calculating Keq for a reaction: 2SO2(g) + O2(g)2SO3(g) At equilibrium: [SO2 ] = 1.50M [O2 ] = 1.25M [SO3] = 3.50M

4. Calculating Keq for a reaction: 2SO2(g) + O2(g)2SO3(g) At equilibrium: [SO2 ] = 0.590M [O2 ] = 0.045M [SO3 ] = 0.260M

5. Calculate the equilibrium constant for the following reaction. 3H2(g) + N2(g) 2NH3(g) if at 25ºC there 0.15 mol of N2 , 0.25 mol of NH3 , and 0.10 mol of H2 in a 2.0 L container.

6. there 0.15 mol of N2 , 0.25 mol of NH3 , and 0.10 mol of H2 in a 2.0 L container. Change moles to molarity: [N2] = 0.15 mol/2.0L = 0.075 M [H2] = 0.10 mol/2.0L = 0.050 M [NH3] = 0.25 mol/2.0L = 0.125 M

7. Calculate the equilibrium constant. • Given N2 (g) + 3H2 (g) 2NH3 (g) • At 200ºC, the concentration of nitrogen is 2.12 M, the concentration of hydrogen is 1.75 M, and ammonia is 84.3 M, calculate the equilibrium constant.

9. Given PCl5 (g) PCl3 (g) + Cl2 (g) • Calculate the equilibrium constant of PCl3 and Cl2, if the equilibrium concentration for PCl5 is 0.32 M and the equilibrium constant is 0.50.

10. Cross multiply The concentration of PCl3 and Cl2 is 0.40 M

11. Calculate the equilibrium concentration at 400ºC of NH3, for the reaction: N2 (g) + 3H2 (g) 2NH3 (g) • The equilibrium concentrations for [N2] = 0.45 and [H2] = 1.10. • The keq, at this temperature, is 1.7 x 10-2.

12. Cross multiply

13. Questions p 559 # 1-4, # 6-9