University of Texas, Arlington CHEM 1442 Chapter 14 Questions Equilibrium Problems with NO x(variable) – Numbers only problems 1)For the reaction given below, 3 moles of A and 4 moles of B are placed in a 5 L flask

Equilibrium Problems with x - you must solve for x

3.         The equilibrium constant, K_p, for the reaction: 2HCN(g) ? H₂(g) + C₂N₂(g) is 4 X 10^-4. What is the equilibrium partial pressure of C₂N₂ if pure HCN was               originally present at 25 atm?

4. For the reaction below, K = 0.25. If one mole of each A, B, and C is placed in                        a1L flask, what is the equilibrium concentration of C? A(g) + B(g) ? 2C(g)
5. A weak acid, HA, has a Keq of 1.8 X 10^-5. What is the H⁺ concentration at equilibrium if the initial concentration is 0.15 M? Reaction: HA → H⁺ + A^-

Le Chatelier’s Principle

6. The equilibrium reaction: n-butane ? Iso-butane has a K value of 2.5 at 25^oC.                    If 1 M of n-butane and 2.9 M of iso-butane are mixed together in a bulb at 25^oC,     which of the following statements is correct?
   1. the system is at equilibrium (b) the concentration of n-butane will decrease

when equilibrium is attained (c) the concentration of n-butane will increase when equilibrium is attained

(d) cannot predict what will happen.

7.            A(s) + 2B(g) ? 3C(g) ?H = -20 kJ

Will the following cause the reaction to shift right or left: (a) Add small amount                 of A (b) cool the vessel (c) increase the size of the vessel (d) add B (e) remove                                                C (f) add He to vessel

8. 2A(g) + B(s) ? 3C(g) With each of the following changes, which way will the reaction shift (right or left) and will the concentration of C increase, decrease, or stay the same at equilibrium. (a) Add A (b) remove B (c) heat the reaction( ?H for the reaction is 10 J.) (d) add 1 atm He (e) remove some C

How Changing the equation will change the value of K

9. For the reaction:  2A + B ? 3C, K = 4. What is the value of K for the                         following: (a) 3C ? 2A + B
   2. 4A + 2B ? 6C

10. Consider the following two equilibria:

SO₂(g) + 0.5 O₂(g) ? SO₃(g) = K₁ and 2SO₃(g) ? 2SO₂(g) + O₂(g) = K₂

Which of the following represents the relation of K₁ to the second equation?                  (a) K₂ = K ² (b) K ²

= K₁ (c) K₂ = K₁ (d) K₂ = 1/K₁ (d) K₂ = 1/K ²

Extra concept using the quadratic equation to solve equilibrium problems

11. In the reaction below, we begin with 2 M CO and 1 .M H₂O. CO(g) + H₂O(g) → CO₂(g) + H₂(g)              K_c = 1.56 What is the equilibrium value of CO₂?