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Chapter 13- Chemical Equilibrium

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Originally chapter 15
Dawn G
Quiz by Dawn G, updated more than 1 year ago
Dawn G
Created by Dawn G almost 8 years ago
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Question 1

Question
At equilibrium, __________.
Answer
  • A) all chemical reactions have ceased
  • B) the rates of the forward and reverse reactions are equal
  • C) the rate constants of the forward and reverse reactions are equal
  • D) the value of the equilibrium constant is 1
  • E) the limiting reagent has been consumed

Question 2

Question
Which one of the following will change the value of an equilibrium constant?
Answer
  • A) changing temperature
  • B) adding other substances that do not react with any of the species involved in the equilibrium
  • C) varying the initial concentrations of reactants
  • D) varying the initial concentrations of products
  • E) changing the volume of the reaction vessel

Question 3

Question
The equilibrium-constant expression depends on the __________ of the reaction.
Answer
  • A) stoichiometry
  • B) mechanism
  • C) stoichiometry and mechanism
  • D) the quantities of reactants and products initially present
  • E) temperature

Question 4

Question
The equilibrium constant for reaction 1 is K. The equilibrium constant for reaction 2 is __________. (1) SO2 (g) + (1/2) O2 (g) --> SO3 (g) (2) 2SO3 (g) --> 2SO2 (g) + O2 (g)
Answer
  • A) K2
  • B) 2K
  • C) 1/2K
  • D) 1/K2
  • E) -K2

Question 5

Question
The value of Keq for the following reaction is 0.25: SO2 (g) + NO2 (g) ---> SO3 (g) + NO (g) The value of Keq at the same temperature for the reaction below is __________. 2SO2 (g) + 2NO2 (g) ---> 2SO3 (g) + 2NO (g)
Answer
  • A) 0.50
  • B) 0.063
  • C) 0.12
  • D) 0.25
  • E) 16

Question 6

Question
The Keq for the equilibrium below is 7.52 × 10-2 at 480.0°C. 2Cl2 (g) + 2H2O (g) --> 4HCl (g) + O2 (g) What is the value of Keq at this temperature for the following reaction? 4HCl (g) + O2 (g) --> 2Cl2 (g) + 2H2O (g)
Answer
  • A) 0.0752
  • B) -0.0752
  • C) 13.3
  • D) 5.66 × 10-3
  • E) 0.150

Question 7

Question
Given the following reaction at equilibrium, if Kc = 1.90 × 1019 at 25.0°C, Kp = __________. H2 (g) + Br2 (g) ---> 2 HBr (g)
Answer
  • A) 5.26 × 10-20
  • B) 1.56 × 104
  • C) 6.44 × 105
  • D) 1.90 × 1019
  • E) none of the above

Question 8

Question
The equilibrium constant for the gas phase reaction N2 (g) + 3H2 (g) --> 2NH3 (g) is Keq = 4.34 × 10-3 at 300°C. At equilibrium, __________.
Answer
  • A) products predominate
  • B) reactants predominate
  • C) roughly equal amounts of products and reactants are present
  • D) only products are present
  • E) only reactants are present

Question 9

Question
The equilibrium constant for the gas phase reaction 2SO2 (g) + O2 (g) --> 2SO3 (g) is Keq = 2.80 × 102 at 999 K. At equilibrium, __________.
Answer
  • A) products predominate
  • B) reactants predominate
  • C) roughly equal amounts of products and reactants are present
  • D) only products are present
  • E) only reactants are present

Question 10

Question
Consider the following equilibrium. 2SO2 (g) + O2 (g) --> 2SO3 (g) The equilibrium cannot be established when __________ is/are placed in a 1.0-L container.
Answer
  • A) 0.25 mol SO2 (g) and 0.25 mol O2 (g)
  • B) 0.75 mol SO2 (g)
  • C) 0.25 mol of SO2 (g) and 0.25 mol of SO3 (g)
  • D) 0.50 mol O2 (g) and 0.50 mol SO3 (g)
  • E) 1.0 mol SO3 (g)

Question 11

Question
At 400 K, the equilibrium constant for the reaction Br2 (g) + Cl2 (g) --> 2BrCl (g) is Kp = 7.0. A closed vessel at 400 K is charged with 1.00 atm of Br2 (g), 1.00 atm of Cl2 (g), and 2.00 atm of BrCl (g). Use Q to determine which of the statements below is true.
Answer
  • A) The equilibrium partial pressures of Br2, Cl2, and BrCl will be the same as the initial values.
  • B) The equilibrium partial pressure of Br2 will be greater than 1.00 atm.
  • C) At equilibrium, the total pressure in the vessel will be less than the initial total pressure.
  • D) The equilibrium partial pressure of BrCl (g) will be greater than 2.00 atm.
  • E) The reaction will go to completion since there are equal amounts of Br2 and Cl2.

Question 12

Question
How is the reaction quotient used to determine whether a system is at equilibrium?
Answer
  • A) The reaction quotient must be satisfied for equilibrium to be achieved.
  • B) At equilibrium, the reaction quotient is undefined.
  • D) The reaction is at equilibrium when Q > Keq.
  • E) The reaction is at equilibrium when Q = Keq.

Question 13

Question
Of the following equilibria, only __________ will shift to the right in response to a decrease in volume.
Answer
  • A) H2 (g) + Cl2 (g) ---> 2 HCl (g)
  • B) 2 SO3 (g) ---> 2 SO2 (g) + O2 (g)
  • C) N2 (g) + 3 H2 (g) ---> 2 NH3 (g)
  • D) 2 Fe2O3 (s) ---> 4 Fe (s) + 3 O2 (g)
  • E) 2HI (g) ---> H2 (g) + I2 (g)

Question 14

Question
The reaction below is exothermic: 2SO2 (g) + O2 (g) ---> 2SO3 (g) Le Châtelier's Principle predicts that __________ will result in an increase in the number of moles of SO3 (g) in the reaction container.
Answer
  • A) increasing the pressure
  • B) decreasing the pressure
  • C) increasing the temperature
  • D) removing some oxygen
  • E) increasing the volume of the container

Question 15

Question
For the endothermic reaction CaCO3 (s) --> CaO (s) + CO2 (g) Le Châtelier's principle predicts that __________ will result in an increase in the number of moles of CO2.
Answer
  • A) increasing the temperature
  • B) decreasing the temperature
  • C) increasing the pressure
  • D) removing some of the CaCO3 (s)
  • E) none of the above

Question 16

Question
In which of the following reactions would increasing pressure at constant temperature not change the concentrations of reactants and products, based on Le Châtelier's principle?
Answer
  • A) N2 (g) + 3H2 (g) 2NH3 (g)
  • B) N2O4 (g) 2NO2 (g)
  • C) N2 (g) + 2O2 (g) 2NO2 (g)
  • D) 2N2 (g) + O2 (g) 2N2O (g)
  • E) N2 (g) + O2 (g) 2NO (g)

Question 17

Question
Consider the following reaction at equilibrium: 2NH3 (g) ---> N2 (g) + 3H2 (g) ΔH° = +92.4 kJ Le Châtelier's principle predicts that adding N2 (g) to the system at equilibrium will result in __________.
Answer
  • A) a decrease in the concentration of NH3 (g)
  • B) a decrease in the concentration of H2 (g)
  • C) an increase in the value of the equilibrium constant
  • D) a lower partial pressure of N2
  • E) removal of all of the H2 (g)

Question 18

Question
Consider the following reaction at equilibrium: 2NH3 (g) ----> N2 (g) + 3H2 (g) Le Châtelier's principle predicts that the moles of H2 in the reaction container will increase with __________.
Answer
  • A) some removal of NH3 from the reaction vessel (V and T constant)
  • B) a decrease in the total pressure (T constant)
  • C) addition of some N2 to the reaction vessel (V and T constant)
  • D) a decrease in the total volume of the reaction vessel (T constant)
  • E) an increase in total pressure by the addition of helium gas (V and T constant)

Question 19

Question
Consider the following reaction at equilibrium: 2CO2 (g) ---> 2CO (g) + O2 (g) ΔH° = -514 kJ Le Châtelier's principle predicts that adding O2 (g) to the reaction container will __________.
Answer
  • A) increase the partial pressure of CO (g) at equilibrium
  • B) decrease the partial pressure of CO2 (g) at equilibrium
  • C) increase the value of the equilibrium constant
  • D) increase the partial pressure of CO2 (g) at equilibrium
  • E) decrease the value of the equilibrium constant

Question 20

Question
Consider the following reaction at equilibrium: 2CO2 (g) ----> 2CO (g) + O2 (g) ΔH° = -514 kJ Le Châtelier's principle predicts that an increase in temperature will __________.
Answer
  • A) increase the partial pressure of O2 (g)
  • B) decrease the partial pressure of CO2 (g)
  • C) decrease the value of the equilibrium constant
  • D) increase the value of the equilibrium constant
  • E) increase the partial pressure of CO

Question 21

Question
Consider the following reaction at equilibrium: C (s) + H2O (g) ----> CO (g) + H2 (g) Which of the following conditions will increase the partial pressure of CO?
Answer
  • A) decreasing the partial pressure of H2O (g)
  • B) removing H2O (g) from the system
  • C) decreasing the volume of the reaction vessel
  • D) decreasing the pressure in the reaction vessel
  • E) increasing the amount of carbon in the system

Question 22

Question
Consider the following reaction at equilibrium. 2CO2 (g) ---> 2CO (g) + O2 (g) ΔH° = -514 kJ Le Châtelier's principle predicts that the equilibrium partial pressure of CO (g) can be maximized by carrying out the reaction __________.
Answer
  • A) at high temperature and high pressure
  • B) at high temperature and low pressure
  • C) at low temperature and low pressure
  • D) at low temperature and high pressure
  • E) in the presence of solid carbon

Question 23

Question
Consider the following reaction at equilibrium: 2SO2 (g) + O2 (g) --> 2SO3 (g) ΔH° = -99 kJ Le Châtelier's principle predicts that an increase in temperature will result in __________.
Answer
  • A) a decrease in the partial pressure of SO3
  • B) a decrease in the partial pressure of SO2
  • C) an increase in Keq
  • D) no changes in equilibrium partial pressures
  • E) the partial pressure of O2 will decrease

Question 24

Question
The effect of a catalyst on an equilibrium is to __________.
Answer
  • A) increase the rate of the forward reaction only
  • B) increase the equilibrium constant so that products are favored
  • C) slow the reverse reaction only
  • D) increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture
  • E) shift the equilibrium to the right

Question 25

Question
The value of Keq for the equilibrium H2 (g) + I2 (g) ---> 2 HI (g) is 794 at 25 °C. What is the value of Keq for the equilibrium below? 1/2 H2 (g) + 1/2 I2 (g) ---> HI (g)
Answer
  • A) 397
  • B) 0.035
  • C) 28
  • D) 1588
  • E) 0.0013

Question 26

Question
The value of Keq for the equilibrium H2 (g) + I2 (g) ---> 2 HI (g) is 794 at 25°C. At this temperature, what is the value of Keq for the equilibrium below? HI (g) ---> 1/2 H2 (g) + 1/2 I2 (g)
Answer
  • A) 1588
  • B) 28
  • C) 397
  • D) 0.035
  • E) 0.0013

Question 27

Question
Given the following reaction: CO (g) + 2H2(g) ---> CH3OH (g) In an experiment, 0.42 mol of CO and 0.42 mol of H2 were placed in a 1.00-L reaction vessel. At equilibrium, there were 0.29 mol of CO remaining. Keq at the temperature of the experiment is __________.
Answer
  • A) 2.80
  • B) 0.357
  • C) 14.5
  • D) 17.5
  • E) none of the above

Question 28

Question
At 200°C, the equilibrium constant (Kp) for the reaction below is 2.40 × 103. 2NO (g) ---> N2 (g) + O2 (g) A closed vessel is charged with 36.1 atm of NO. At equilibrium, the partial pressure of O2 is __________ atm.
Answer
  • A) 294
  • B) 35.7
  • C) 17.9
  • D) 6.00
  • E) 1.50 × 10-2

Question 29

Question
Given the following reaction at equilibrium, if Kc = 6.34 x 105 at 230.0°C, Kp = __________. 2NO (g) + O2 (g) ---> 2NO2 (g)
Answer
  • A) 3.67 × 10-2
  • B) 1.53 × 104
  • C) 6.44 × 105
  • D) 2.61 × 106
  • E) 2.62 × 107

Question 30

Question
Nitrosyl bromide decomposes according to the following equation. 2NOBr (g) ---> 2NO (g) + Br2 (g) A sample of NOBr (0.64 mol) was placed in a 1.00-L flask containing no NO or Br2. At equilibrium the flask contained 0.36 mol of NOBr. How many moles of NO and Br2, respectively, are in the flask at equilibrium?
Answer
  • A) .28,.28
  • B) .36,.18
  • C) .28,.14
  • D) .14,.23
  • E) .36,.36

Question 31

Question
If the value for the equilibrium constant is much greater than 1, then the equilibrium mixture contains mostly __________.
Answer
  • A) Reactants
  • B) Products
  • C) Neither, they are in equal amounts

Question 32

Question
The number obtained by substituting starting reactant and product concentrations into an equilibrium-constant expression is known as the __________.
Answer
  • A) Rate Constant
  • B) Reaction Quotient
  • C) Equilibrium Concentration
  • D) Reaction Rate

Question 33

Question
The relationship between the concentrations of reactants and products of a system at equilibrium is given by the law of mass action.
Answer
  • True
  • False

Question 34

Question
If a reaction is endothermic, __________ the reaction temperature results in an increase in K.
Answer
  • A) Increasing
  • B) Decreasing
  • C) Constant

Question 35

Question
For an exothermic reaction, increasing the reaction temperature results in a(an) __________ in K.
Answer
  • A) Increasing
  • B) Decreasing
  • C) Constant
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