Question

Chemistry 202 Worksheet -Equilibrium Worksheet Grade: Name: K,= POP" Key concepts 1. Equilibrium is the state at which the concentrations of the reactants and products remain constant over time. Equilibrium is often defined in terms of Ke or Kp, the equilibrium constants in terms of concentration or partial pressure, respectively. For aA + bB - C + dD: [C]*[D]" [A]"[B]" The two constants are related to each other for a given reaction by: K = K (RT).. (Use R = 0.0821 L atm/mol K.) 2. All equilibrium reactions want to remain in equilibrium. According to Le Châtelier's Principle, any thing we do to the reaction that disrupts the equilibrium, will cause the reaction to try and minimize the change: • Adding more reactant or product, will shift the equilibrium to reduce it. Taking away reactant or product, will shift the equilibrium to replace it. Treat heat as if it was a product (for exothermic reactions) or a reactant (for endothermic reactions) when increasing or decreasing the temperature. Increasing pressure (by decreasing volume) will shift the equilibrium to the side of the reaction with the least number of moles of gas. [Decreasing pressure will have the opposite affect, the reaction shifts to the side with the most moles of gas.] Solve the following problems. 1. Consider a simple reaction: A (g) - B (g) Where rate forward = kr[A] and rate reverse = k[B] [A]. B7 kf 0.20 0.20 0.60 0.60 0.50 IN 33 33 150 0.40 0.40 0.20 0.20 0.50 200 50 150 100 50 80 20 0.20 0.20 24 0.60 0.60 41 24 a. What is the distinction between [A], and [A] in the column heading? b. For Trial M2, calculate the rate of the forward reaction ( A B) at equilibrium and the rate of the reverse reaction ( B A) at equilibrium. How do these values compare?

Answer 1

[ A ] the as The Reaction initial has not Concentration when started I - [A] is The Concentration at the time y equill birum. Rate of forward Reaction = ke[A] Rate of Backward Reaction = kr [8] Rake of forward Reaction = 67 [020] = 13-4 Moll's! Rate of Backward Reaction = 33 [0.40] = 13²4 Moll's Pote od lorward Reaction - Rate of backward ! Reaction, which proves that Reection is at equillibirium