1 (301)

Prévia do material em texto

Chapter 15 Chemical Equilibrium 301 (b) Given: [A] = 1.0 M, [B] = 0.0, = 4.0; a = Find: [A], [B] at equilibrium Conceptual Plan: Prepare an ICE table, calculate Q, compare Q and Kc, predict the direction of the reac- tion, represent the change with x, sum the table, determine the equilibrium values, put the equilibrium values in the equilibrium expression, and solve for x. Determine [A] and [B]. Solution: 2A(g) 2B(g) [A] [B] Initial 1.0 0.00 Change -2x +2x Equil 1.0 - 2x 2x Q = = 1.0 0 = 0 Therefore, the reaction will proceed to the right by = = (1.0 = 4.0 = V4.0 Take the square root of this expression. x = 0.33 (1.0 [A] = 1 - 2(0.33) = 0.34 M; [B] = 2(0.33) = 0.66 M Check: Plug the values into the equilibrium expression: Kc = (0.66)² = 3.8. (c) Given: [A] = [B] = 0.0, Kc = 4.0; a = 1,b = 2 Find: [A], [B] at equilibrium Conceptual Plan: Prepare an ICE table, calculate Q, compare Q and Kc, predict the direction of the reac- tion, represent the change with x, sum the table, determine the equilibrium values, put the equilibrium values in the equilibrium expression, and solve for x. Determine [A] and [B]. Solution: A(g) 2B(g) [A] [B] Initial 1.0 0.00 Change -x +2x Equil 1.0 - x 2x [B]² 0 = [A] = 1.0 = 0 Therefore, the reaction will proceed to the right by Kc = [B]² [A] = = 4.0 + 4x - 4 = 0 Solve using the quadratic equation, found in Appendix I. x = 1.6 or x = 0.62; therefore, x = 0.62. [A] = 1.0 0.62 = 0.38 M [B] = 2x = 2(0.62) = M Check: Plug the values into the equilibrium expression: = (1.2)² 0.38 = 3.8. 15.53 Given: [N₂O₄] = 0.0500 M, [NO₂] = 0.0, Kc = 0.513 Find: [N₂O₄], [NO₂] at equilibrium Conceptual Plan: Prepare an ICE table, calculate Q, compare Q and Kc, predict the direction of the reaction, represent the change with x, sum the table, determine the equilibrium values, put the equilibrium values in the equilibrium expression, and solve for x. Determine [N₂O₄] and [NO₂]. Solution: 1L [N₂O₄] [NO₂] Initial 0.0500 0.00 Change -x +2x Equil 0.0500 - x 2x Q = = 0 = 0 [N₂O₄] 0.0500 Therefore, the reaction will proceed to the right by x. Copyright © 2017 Pearson Education, Inc.