Question 1

Both products and reactants will be present in an equilibrium reaction unless K is very small or very large.

Accepted Answer

A) True 
 B)False

Question 2

2.5 moles H2O and 100 g of C are placed in a 50-L container. At equilibrium for the reaction C(s) + H2O(g) ⇌ CO(g) + H2(g), [H2] = 0.040 M. Which of the following is true?

Accepted Answer

A)  [CO] = 0.020 M 
B)  [H2O] = 0.010 M 
C)  no carbon is left 
D)  [H2O] = 0.020 M 
E)  [C(s)] = 0.04 M 
A)  [CO] = 0.020 M 
B)  [H2O] = 0.010 M 
C)  no carbon is left 
D)  [H2O] = 0.020 M 
E)  [C(s)] = 0.04 M

Question 3

In a reaction at equilibrium involving only gases, a pressure change will shift the reaction only when:

Accepted Answer

A)  heat is absorbed by the reaction proceeding to the right 
B)  the number of molecules on one side is greater than the number on the other side of the balanced equation 
C)  the number of molecules increases during the chemical reaction 
D)  the gases are impure 
E)  the collision rate increases 
A)  heat is absorbed by the reaction proceeding to the right 
B)  the number of molecules on one side is greater than the number on the other side of the balanced equation 
C)  the number of molecules increases during the chemical reaction 
D)  the gases are impure 
E)  the collision rate increases

Question 4

For the reaction below CO(g) + 2H2(g) ⇌ CH3OH(g)
The equilibrium concentrations at 483 K are [CO(g)] = 0.0753 M, [H2(g)] = 0.151 M, and [CH3OH(g)] = 0.0247 M. Calculate the value of Kc.

Accepted Answer

A)  14.4 
B)  1.09 
C)  2.17 
D)  0.0694 
A)  14.4 
B)  1.09 
C)  2.17 
D)  0.0694

Question 5

For the reaction: 2 SO2(g) + O2(g) ⇌ 2 SO3(g), Kc = 6.9 × 1024 at 25°C. If a reaction vessel is filled with these gases, such that [SO2] = 6.0 M, [O2] = 6.0 M and [SO3] = 6.0 M, in which direction will the reaction proceed?

Accepted Answer

A)  The reaction proceeds to the right. 
B)  The reaction proceeds to the left. 
C)  The reaction is already at equilibrium. 
D)  The reaction volume must be specified to answer this question. 
E)  The value of Kp must be specified to answer this question. 
A)  The reaction proceeds to the right. 
B)  The reaction proceeds to the left. 
C)  The reaction is already at equilibrium. 
D)  The reaction volume must be specified to answer this question. 
E)  The value of Kp must be specified to answer this question.

Question 6

For the reaction: CH4(g) + 2 H2O(g) ⇌ CO2(g) + 4 H2(g) ΔH° = +190 kJ when CH4 is added:

Accepted Answer

A)  the reaction reacts to the right 
B)  the reaction reacts to the left 
C)  the ΔH° increases 
D)  the temperature increases 
E)  there is no change in equilibrium position 
A)  the reaction reacts to the right 
B)  the reaction reacts to the left 
C)  the ΔH° increases 
D)  the temperature increases 
E)  there is no change in equilibrium position

Question 7

Equilibrium constant K is constant except when one varies the:

Accepted Answer

A)  concentrations of the reactants 
B)  temperature of the reaction 
C)  concentration of the products 
D)  partial pressures of the reactants 
E)  K always remains constant 
A)  concentrations of the reactants 
B)  temperature of the reaction 
C)  concentration of the products 
D)  partial pressures of the reactants 
E)  K always remains constant

Question 8

What will happen to the equilibrium in the reaction 2 A(g) ⇌ B(g) + C(g), Kc = 1.25 at 300 K if a catalyst is added?

Accepted Answer

A)  The reaction is forced to the right. 
B)  The reaction is forced to the left. 
C)  No change, catalyst only changes the rate. 
D)  Kc is increased. 
E)  Kc is decreased. 
A)  The reaction is forced to the right. 
B)  The reaction is forced to the left. 
C)  No change, catalyst only changes the rate. 
D)  Kc is increased. 
E)  Kc is decreased.

Question 9

One of the reactions in the gasification of coal is
CO(g) + 3H2(g) ⇌ CH4(g) + H2O(g) ΔH° = -237 kJ
For each of the following changes, explain the effect (increase, decrease, no effect) on the number of moles of CH4(g) produced.
A) increase the concentration of H2O(g)
B) decrease the volume of the container
C) add a catalyst
D) decrease the temperature

Accepted Answer

A) decrease, 
B) inc

Question 10

What is the relationship between Kp and Kc for the reaction below? 4NH3(g) + 7O2(g) ⇌ 2N2O4(g) + 6H2O(g)

Accepted Answer

A)  Kp = Kc(RT)-3 
B)  Kc = Kp(RT)-3 
C)  Kp = Kc(RT)3 
D)  Kp = Kc(RT) 
A)  Kp = Kc(RT)-3 
B)  Kc = Kp(RT)-3 
C)  Kp = Kc(RT)3 
D)  Kp = Kc(RT)

Question 11

Consider the following reaction occurring at 960 K: CO2(g) + H2(g) ⇌ CO(g) + H2O(g)
At equilibrium, the concentrations of reactants and products are: [CO2] = 0.0400 M, [H2] = 0.0220 M, [CO] = 0.0240 M, and [H2O] = 0.0190 M. This equilibrium is perturbed by adding CO2(g) to the system such that when a new equilibrium is reached, the concentration of CO2 is 0.050 M. What is the concentration of H2(g) at this equilibrium?

Accepted Answer

A)  0.050 M 
B)  0.482 M 
C)  0.462 M 
D)  0.300 M 
E)  0.0504 M 
A)  0.050 M 
B)  0.482 M 
C)  0.462 M 
D)  0.300 M 
E)  0.0504 M

Question 12

For the decomposition of ammonium carbamate NH4(NH2CO2)(s) ⇌ 2NH3(g) + CO2(g)
Kp = 0.0596 at a certain temperature. A solid sample of ammonium carbamate is introduced into an evacuated container and at equilibrium some solid remains in the container. What is the total pressure in the container?

Accepted Answer

A)  0.738 atm 
B)  1.17 atm 
C)  0.930 atm 
D)  0.179 atm 
A)  0.738 atm 
B)  1.17 atm 
C)  0.930 atm 
D)  0.179 atm

Question 13

For the reaction 2 A(g) ⇌ B(g) + C(g), Kc = 1.25 at 300 K. If a 1.00 L mixture contains 0.619 mol A, 0.693 mol B, and 0.689 mol C at 300 K, will the mixture be in equilibrium? If not, in what direction will a net reaction occur?

Accepted Answer

A)  Yes, at equilibrium. 
B)  No, net reaction to the left. 
C)  No, net reaction to the right. 
D)  No, but there is no net reaction. 
E)  Yes, net reaction to the right 
A)  Yes, at equilibrium. 
B)  No, net reaction to the left. 
C)  No, net reaction to the right. 
D)  No, but there is no net reaction. 
E)  Yes, net reaction to the right

Question 14

Equilibrium reactions are noted by a single straight arrow for a yield sign.

Accepted Answer

A) True 
 B)False

Question 15

Write the equilibrium constant expression for the following reaction: N2(g) + 3 H2(g) ⇌ 2 NH3(g)

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 16

Consider the reaction: 2SO2(g) + O2(g) ⇌ 2SO3(g) ΔH° = -196.6 kJ/mol
The equilibrium is displaced to the left if:

Accepted Answer

A)  some sulfur trioxide is removed 
B)  the temperature is raised 
C)  some sulfur dioxide is added 
D)  the pressure is raised 
E)  the temperature is lowered 
A)  some sulfur trioxide is removed 
B)  the temperature is raised 
C)  some sulfur dioxide is added 
D)  the pressure is raised 
E)  the temperature is lowered

Question 17

Consider the following equilibrium. A(g) + 3B(g) ⇌ 2C(g)
If the initial concentrations are [A(g)] = 1.00 M, [B(g)] = 3.00 M, and [C(g)] = 0, at equilibrium it is found that [C(g)] = 0.980 M. Calculate Kc for this reaction.

Accepted Answer

A)  0.526 
B)  0.268 
C)  1.26 
D)  0.131 
A)  0.526 
B)  0.268 
C)  1.26 
D)  0.131

Question 18

For the reaction: 3 Fe(s) + 4 H2O(g) ⇌ Fe3O4(s) + 4 H2(g) write the expression for Kc in terms of Kp.

Accepted Answer

A)  Kc = Kp 
B)  Kc =   
C)  Kc = KpRT 
D)  Kc = Kp2 
E)  Kc =   
A)  Kc = Kp 
B)  Kc =   
C)  Kc = KpRT 
D)  Kc = Kp2 
E)  Kc =

Question 19

For the reaction: 3 Fe(s) + 4 H2O(g) ⇌ Fe3O4(s) + 4 H2(g) what is the effect of removing H2?

Accepted Answer

A)  The reaction shifts to the right. 
B)  There is no change. 
C)  The reaction shifts to the left. 
D)  The Kp is decreased. 
E)  The Kp is doubled. 
A)  The reaction shifts to the right. 
B)  There is no change. 
C)  The reaction shifts to the left. 
D)  The Kp is decreased. 
E)  The Kp is doubled.

Exam 15: Principles of Chemical Equilibrium

Both products and reactants will be present in an equilibrium reaction unless K is very small or very large.

2.5 moles H2O and 100 g of C are placed in a 50-L container. At equilibrium for the reaction C(s) + H2O(g) ⇌ CO(g) + H2(g), [H2] = 0.040 M. Which of the following is true?

In a reaction at equilibrium involving only gases, a pressure change will shift the reaction only when:

For the reaction below CO(g) + 2H2(g) ⇌ CH3OH(g) The equilibrium concentrations at 483 K are [CO(g)] = 0.0753 M, [H2(g)] = 0.151 M, and [CH3OH(g)] = 0.0247 M. Calculate the value of Kc.

For the reaction: 2 SO2(g) + O2(g) ⇌ 2 SO3(g), Kc = 6.9 × 1024 at 25°C. If a reaction vessel is filled with these gases, such that [SO2] = 6.0 M, [O2] = 6.0 M and [SO3] = 6.0 M, in which direction will the reaction proceed?

For the reaction: CH4(g) + 2 H2O(g) ⇌ CO2(g) + 4 H2(g) ΔH° = +190 kJ when CH4 is added:

Equilibrium constant K is constant except when one varies the:

What will happen to the equilibrium in the reaction 2 A(g) ⇌ B(g) + C(g), Kc = 1.25 at 300 K if a catalyst is added?

What is the relationship between Kp and Kc for the reaction below? 4NH3(g) + 7O2(g) ⇌ 2N2O4(g) + 6H2O(g)

For the decomposition of ammonium carbamate NH4(NH2CO2)(s) ⇌ 2NH3(g) + CO2(g) Kp = 0.0596 at a certain temperature. A solid sample of ammonium carbamate is introduced into an evacuated container and at equilibrium some solid remains in the container. What is the total pressure in the container?

For the reaction 2 A(g) ⇌ B(g) + C(g), Kc = 1.25 at 300 K. If a 1.00 L mixture contains 0.619 mol A, 0.693 mol B, and 0.689 mol C at 300 K, will the mixture be in equilibrium? If not, in what direction will a net reaction occur?

Equilibrium reactions are noted by a single straight arrow for a yield sign.

Write the equilibrium constant expression for the following reaction: N2(g) + 3 H2(g) ⇌ 2 NH3(g)

Consider the reaction: 2SO2(g) + O2(g) ⇌ 2SO3(g) ΔH° = -196.6 kJ/mol The equilibrium is displaced to the left if:

Consider the following equilibrium. A(g) + 3B(g) ⇌ 2C(g) If the initial concentrations are [A(g)] = 1.00 M, [B(g)] = 3.00 M, and [C(g)] = 0, at equilibrium it is found that [C(g)] = 0.980 M. Calculate Kc for this reaction.

For the reaction: 3 Fe(s) + 4 H2O(g) ⇌ Fe3O4(s) + 4 H2(g) write the expression for Kc in terms of Kp.

For the reaction: 3 Fe(s) + 4 H2O(g) ⇌ Fe3O4(s) + 4 H2(g) what is the effect of removing H2?

Matter - Its Properties and Measurement

Atoms and the Atomic Theory

Chemical Compounds

Chemical Reactions

Introduction to Reactions in Aqueous Solutions

Gases

Thermochemistry

Electrons in Atoms

The Periodic Table and Some Atomic Properties

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Additional Aspects

Intermolecular Forces: Liquids and Solids

Solutions and Their Physical Properties

Chemical Kinetics

Acids and Bases

Additional Aspects of Acid-Base Equilibria

Solubility and Complex-Ion Equilibria

Spontaneous Change: Entropy and Free Energy

Electrochemistry

Main Group Elements I: Groups 1, 2, 13, and 14

Main Group Elements II: Groups 18, 17, 16, 15, and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry 1-41

Structures of Organic Compounds

Reactions of Organic Compounds

Chemistry of the Living State

Filters

2.5 moles H₂O and 100 g of C are placed in a 50-L container. At equilibrium for the reaction C(s) + H₂O(g) ⇌ CO(g) + H₂(g), [H₂] = 0.040 M. Which of the following is true?

For the reaction below CO(g) + 2H₂(g) ⇌ CH₃OH(g) The equilibrium concentrations at 483 K are [CO(g)] = 0.0753 M, [H₂(g)] = 0.151 M, and [CH₃OH(g)] = 0.0247 M. Calculate the value of Kc.

For the reaction: 2 SO₂(g) + O₂(g) ⇌ 2 SO₃(g), Kc = 6.9 × 10²⁴ at 25°C. If a reaction vessel is filled with these gases, such that [SO₂] = 6.0 M, [O₂] = 6.0 M and [SO₃] = 6.0 M, in which direction will the reaction proceed?

For the reaction: CH₄(g) + 2 H₂O(g) ⇌ CO₂(g) + 4 H₂(g) ΔH° = +190 kJ when CH₄ is added:

What is the relationship between Kp and Kc for the reaction below? 4NH₃(g) + 7O₂(g) ⇌ 2N₂O₄(g) + 6H₂O(g)

Write the equilibrium constant expression for the following reaction: N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g)

Consider the reaction: 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) ΔH° = -196.6 kJ/mol The equilibrium is displaced to the left if:

For the reaction: 3 Fe(s) + 4 H₂O(g) ⇌ Fe₃O₄(s) + 4 H₂(g) write the expression for Kc in terms of Kp.

For the reaction: 3 Fe(s) + 4 H₂O(g) ⇌ Fe₃O₄(s) + 4 H₂(g) what is the effect of removing H₂?