Exam 3 Study Guide (13, 14, 15) LATEST 2022.

1. Exam 3 Study Guide (13, 14, 15) LATEST 2022.
hich of the following is true about a system at equilibrium?
A) The concentration(s) of the reactant(s) is equal to the concentration(s) of the
product(s).
B) No new product molecules are formed.
C) The concentration(s) of reactant(s) is constant over time.
D) The rate of the reverse reaction is equal to the rate of the forward reaction and both
rates are equal to zero.
E) None of the above (A-D) is true.
2.
Which of the following is true about chemical equilibrium?
A) It is microscopically and macroscopically static.
B) It is microscopically and macroscopically dynamic.
C) It is microscopically static and macroscopically dynamic.
D) It is microscopically dynamic and macroscopically static.
E) None of these are true about chemical equilibrium.
3.
For a particular system at a particular temperature there equilibrium constant(s) and there
equilibrium position(s).
A) are infinite; is one
B) is one; are infinite
C) is one; is one
D) are infinite; are infinite
E) none of these
4.
For the reaction given below, 2.00 moles of A and 3.00 moles of B are placed in a 6.00-L
container.


At equilibrium, the concentration of A is 0.246 mol/L. What is the concentration of B at
equilibrium?
A) 0.246 mol/L
B) 0.325 mol/L
C) 0.500 mol/L
D) 0.492 mol/L
E) none of these
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
IV. the 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. If the equilibrium constant for A + B C is 0.208, then the equilibrium constant for
2C 2A + 2B is
A) 0.584
B) 4.81
C) 0.416
D) 23.1
E) 0.208

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


C)


D)


E) none of these
8. If, at a given temperature, the equilibrium constant for the reaction H2(g) + Cl2(g) 2HCl(g) is
Kp, then the equilibrium constant for the reaction HCl(g) → H2(g) + Cl2 (g) can be
represented as:
A)

2
B) Kp
C)


D)
E) none of these

9. Apply the law of mass action to determine the equilibrium expression for 2NO2Cl(aq)
2NO2(aq) + Cl2(aq).
A) K = 2[NO2][Cl2]/2[NO2Cl]
B) K = 2[NO2Cl]/2[NO2][Cl2]
C) K = [NO2Cl]2/[NO2]2[Cl2]
D) K = [NO2]2[Cl2]/[NO2Cl]2
E) K = [NO2Cl]2[NO2]2[Cl2]

10. For the reaction N2O4(g) 2NO2(g), Kp = 0.148 at a temperature of 298 K. What is Kp for the
following reaction?
10NO2(g) 5N2O4(g)
A) 6.76
B) 0.74

, C) 1.35
D) 1.41  104
E) 7.10  10–5

11. An equilibrium reaction, A2(g) + 3B2(g) 2C(g), has a Kp at 225°C of 2.6  10–3 /atm2. What is
K for this reaction at that temperature?
A) 1.6  10–6
B) 7.6  10–6
C) 4.3
D) 6.4  10–5
E) 0.89
12. Consider the following reaction: CS2(g) + 4H2(g) CH4(g) + 2H2S(g). The equilibrium
constant K is about 0.31 at 900.°C. What is Kp at this temperature?
A) 2.9  103
B) 3.2  10–3
C) 3.3  10–5
D) 3.0  101
E) 1.1  10–3

Consider the following equilibrium: H2(g) + I2(s) 2HI(g)

13. The proper Keq expression is:
A)

B)


C)


D)


E)


14. Consider the reaction: 2SO2(g) + O2(g) 2SO3(g) at constant temperature. Initially a container
is filled with pure SO3(g) at a pressure of 2 atm, after which equilibrium is reached. If y is the
partial pressure of O2 at equilibrium, the value of Kp is:
A)


B)

, C)


D)

E) none of these

15. Which of the following is true for a system whose equilibrium constant is relatively small?
A) It will take a short time to reach equilibrium.
B) It will take a long time to reach equilibrium.
C) The equilibrium lies to the left.
D) The equilibrium lies to the right.
E) Two of these.

16. The reaction quotient for a system is 7.2  102. If the equilibrium constant for the system is 36,
what will happen as equilibrium is approached?
A) There will be a net gain in product.
B) There will be a net gain in reactant.
C) There will be a net gain in both product and reactant.
D) There will be no net gain in either product or reactant.
E) The equilibrium constant will decrease until it equals the reaction quotient.

Nitric oxide, an important pollutant in air, is formed from the elements nitrogen and oxygen at
high temperatures, such as those obtained when gasoline burns in an automobile engine. At
2000°C, K for the reaction N2(g) + O2(g) 2NO(g) is 0.01.

17. Predict the direction in which the system will move to reach equilibrium at 2000°C if 0.4 moles of
N2, 0.1 moles of O2, and 0.08 moles of NO are placed in a 1.0-liter container.
A) The system remains unchanged.
B) The concentration of NO will decrease; the concentrations of N2 and O2 will
increase.
C) The concentration of NO will increase; the concentrations of N2 and O2 will
decrease.
D) The concentration of NO will decrease; the concentrations of N2 and O2 will
remain unchanged.
E) More information is necessary.
18. A 1-L container originally holds 0.4 mol of N2, 0.1 mol of O2, and 0.08 mole of NO. If the volume
of the container holding the equilibrium mixture of N2, O2, and NO is decreased to 0.5 L without
changing the quantities of the gases present, how will their concentrations change?
A) The concentration of NO will increase; the concentrations of N2 and O2 will
decrease.
B) The concentrations of N2 and O2 will increase; and the concentration of NO will
decrease.
C) The concentrations of N2, O2, and NO will increase.
D) The concentrations of N2, O2, and NO will decrease.
E) There will be no change in the concentrations of N2, O2, and NO.