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Homogeneous equilibria

[C] c  [D] d. P C c  P D d. [A] a  [B] b. P A a  P B b. Homogeneous equilibria. Chemical equilibria in which reactants and products are in the same phase. K c =. K p =. Equilibrium constant expressed in terms of molar concentrations. Equilibrium constant expressed

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Homogeneous equilibria

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  1. [C]c[D]d PCcPDd [A]a[B]b PAaPBb Homogeneous equilibria • Chemical equilibria in which reactants and products are in the same phase Kc = Kp = Equilibrium constant expressed in terms of molar concentrations Equilibrium constant expressed in terms of gas partial pressures

  2. Heterogeneous equilibria • Chemical equilibria in which reactants and products are not in the same phase

  3. Kc = [Ag+]1[Cl-]1 Heterogeneous equilibria • Chemical equilibria in which reactants and products are not in the same phase • The concentrations of pure solids and pure liquids do not, and can not, change • Solids and liquids are left out of the equilibrium constant expression

  4. Q Q K Predicting reaction direction

  5. Predicting reaction direction • If Q < K, reaction moves spontaneously towards products until equilibrium point • If Q > K, reaction moves spontaneously towards reactants until equilibrium point • If reaction is at equilibrium, reaction stays at equilibrium

  6. Predicting reaction direction Q>K Q<K K

  7. → ← Predicting reaction direction 2 NOCl(g) 2 NO(g) + Cl2(g) If Kc = 4.4 x 10-4 at 500 K, determine the direction of the reaction if [NO] = .04 n/L, [Cl2] = .02 n/L and [NOCl] = 1.63 n/L Q < K [NO]2[Cl2] [.04]2[.02] = 1.2 x 10-5 Q = = [NOCl]2 [1.63]2

  8. → ← Predicting reaction direction 2 NOCl(g) 2 NO(g) + Cl2(g) If Kc = 4.4 x 10-4 at 500 K, determine the direction of the reaction if [NO] = .04 n/L, [Cl2] = .02 n/L and [NOCl] = 1.63 n/L Q < K [NO]2[Cl2] [.04]2[.02] = 1.2 x 10-5 Q = = [NOCl]2 [1.63]2 Reaction will proceed spontaneously towards products until the equilibrium point is reached

  9. aA + bB cC + dD → ← [C]c[D]d Q = Q [A]a[B]b Reaction at equilibrium K K Q K Q Reaction tends to form products Reaction tends to form products

  10. aA + bB cC + dD → ← [C]c[D]d Q = Q [A]a[B]b aA + bB = cC + dD K K Q K Q aA + bB > cC + dD aA + bB < cC + dD

  11. → N2 + 3 H2 2 NH3 ← Calculating equilibrium concentrations

  12. → N2 + 3 H2 2 NH3 ← Calculating equilibrium concentrations Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature?

  13. → N2 + 3 H2 2 NH3 ← N2 H2 NH3 .5 .8 Initial concentration .15 Equilibrium concentration Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature?

  14. → N2 + 3 H2 2 NH3 ← Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? N2 H2 NH3 .5 .8 0 Initial concentration .15 Equilibrium concentration

  15. Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? → N2 + 3 H2 2 NH3 ← N2 H2 NH3 .5 .8 0 Initial concentration +.15 Change in concentration .15 Equilibrium concentration

  16. → N2 + 3 H2 2 NH3 ← Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? N2 H2 NH3 .5 .8 0 Initial concentration -.225 +.15 Change in concentration .15 Equilibrium concentration

  17. → N2 + 3 H2 2 NH3 ← Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? N2 H2 NH3 .5 .8 0 Initial concentration -.225 +.15 Change in concentration .15 Equilibrium concentration .15 n/L NH3(3 n/L H2/2 n/L NH3)

  18. Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? → N2 + 3 H2 2 NH3 ← N2 H2 NH3 .5 .8 0 Initial concentration -.225 -.075 +.15 Change in concentration .15 Equilibrium concentration

  19. Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? → N2 + 3 H2 2 NH3 ← N2 H2 NH3 .5 .8 0 Initial concentration -.225 -.075 +.15 Change in concentration .15 Equilibrium concentration .15 n/L NH3(1 n/L N2/2 n/L NH3)

  20. Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? → N2 + 3 H2 2 NH3 ← N2 H2 NH3 .5 .8 0 Initial concentration -.225 -.075 +.15 Change in concentration .15 .575 .425 Equilibrium concentration

  21. Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? → N2 + 3 H2 2 NH3 ← N2 H2 NH3 .5 .8 0 Initial concentration -.225 -.075 +.15 Change in concentration .15 .575 .425 Equilibrium concentration EQUILIBRIUM TABLE

  22. Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? → N2 + 3 H2 2 NH3 ← N2 H2 NH3 .15 .575 .425 Equilibrium concentration FROM EQUILIBRIUM TABLE

  23. Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? → N2 + 3 H2 2 NH3 ← N2 H2 NH3 .15 .575 .425 Equilibrium concentration FROM EQUILIBRIUM TABLE [H2]3 [N2] [NH3]2 K =

  24. Suppose at a certain temperature you combined .5 n/L N2 and .8 n/L H2, and at equilibrium had produced .15 n/L NH3. What is the equilibrium constant for the reaction at this temperature? → N2 + 3 H2 2 NH3 ← N2 H2 NH3 .15 .575 .425 Equilibrium concentration FROM EQUILIBRIUM TABLE [H2]3 [N2] [NH3]2 [.15]2 K = = = .278 [.425] [.575]3

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