Concepts of Equilibrium

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Unit 16 Study Guide
1.Which of the following statements concerning equilibrium is not true? A)A system that is disturbed from an equilibrium condition responds in a manner to restore equilibrium. B)Equilibrium in molecular systems is dynamic, with two opposing processes balancing one another. C)The value of the equilibrium constant for a given reaction mixture is the same regardless of the direction from which equilibrium is attained. D)A system moves spontaneously toward a state of equilibrium. E)The equilibrium constant is independent of temperature.

2.Which of the following statements is true?
A)When two opposing processes are proceeding at identical rates, the system is at equilibrium. B)Catalysts are an effective means of changing the position of an equilibrium. C)The concentration of the products equals that of reactants and is constant at equilibrium. D)An endothermic reaction shifts toward reactants when heat is added to the reaction. E)None of the above statements is true.

3.Indicate the mass action expression for the following reaction: 2X(g) + Y(g) [pic] 3W(g) + V(g) A)[X]2[Y][W]3[V]
B)[pic]
C)[pic]
D)[pic]

4.If, at a given temperature, the equilibrium constant for the reaction H2(g) + Cl2(g) [pic] 2HCl(g) is Kp, then the equilibrium constant for the reaction HCl(g) [pic](1/2) H2(g) + (1/2)Cl2 (g) can be represented as: A)[pic]

B)Kp2
C)[pic]
D)[pic]

5.The value of the equilibrium constant , K, is dependent on I.The temperature of the system.
II.The nature of the reactants and products.
III.The concentration of the reactants.
IVThe concentration of the products.
A)I, II
B)II, III
C)III, IV
D)It is dependent on three of the above choices.
E)It is not dependent on any of the above choices.

6.Apply the law of mass action to determine the equilibrium expression for 2NO2Cl [pic] 2NO2 + Cl2 A)2[NO2][Cl2]/2[NO2Cl]
B)2[NO2Cl]/2[NO2][Cl2]
C)[NO2Cl]2/[NO2]2[Cl2]
D)[NO2]2[Cl2]/[NO2Cl]2
E)[NO2Cl]2[NO2]2[Cl2]

Use the following to answer questions 7-8:
Consider the chemical system CO + Cl2 [pic] COCl2; K = 4.6 × 109 L/mol.

7.How do the equilibrium concentrations of the reactants compare to the equilibrium concentration of the product? A)They are much smaller.
B)They are much bigger.
C)They are about the same.
D)They have to be exactly equal.
E)You can't tell from the information given.

8.If the concentration of the product were to double, what would happen to the equilibrium constant? A)It would double its value.
B)It would become half its current value.
C)It would quadruple its value.
D)It would not change its value.
E)It would depend on the initial conditions of the product.

9.Determine the equilibrium constant for the system N2O4 [pic] 2NO2 at 25oC. The concentrations are shown here: [N2O4] = 2.93e–2 M, [NO2] = 1.41e-2 M. A)4.81e–1
B)2.08
C)1.47e2
D)2.32e–1
E)6.79e–3

10.At 500.0 K, one mole of gaseous ONCl is placed in a one-liter container. At equilibrium it is 7.9% dissociated according to the equation shown here: 2ONCl [pic] 2NO + Cl2. Determine the equilibrium constant. A)2.9e–4

B)3.7e–3
C)8.6e–2
D)9.2e–1
E)3.4e3

11.Consider the reaction H2 + I2 [pic] 2HI whose K = 41.9 at a high temperature. If an equimolar mixture of reactants gives the concentration of the product to be 0.50 M at equilibrium, determine the concentration of the hydrogen. A)1.1e–1 M

B)7.7e–2 M
C)3.9e–2 M
D)1.3e1 M
E)6.0e–3 M

12.Consider the gaseous reaction CO(g) + Cl2(g) [pic] COCl2(g). What is the expression for Kp in terms of K? A)K(RT)
B)K/(RT)
C)K(RT)2
D)...
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