Question 1

In an equilibrium process, the concentrations of products and of reactants are equal.

Accepted Answer

A) True 
 B)False

Question 2

Which of the following substances present in the chemical reaction would be excluded from the equilibrium constant expression?

Accepted Answer

A)  Na+ (aq) 
B)  H2O(g) 
C)  Cl- 
D)  H2O(l) (reactant and solvent) 
E)  CO(g) 
A)  Na+ (aq) 
B)  H2O(g) 
C)  Cl- 
D)  H2O(l) (reactant and solvent) 
E)  CO(g)

Question 3

For the reaction; N2(g) + 3 H2(g) ⇌ 2 NH3(g), the equilibrium amount of NH3 will be increased by: 
I. increasing the pressure
II. adding H2
III. removing N2
IV. decreasing the pressure

Accepted Answer

A)  I, III 
B)  III only 
C)  II, III 
D)  I, II 
E)  II, IV 
A)  I, III 
B)  III only 
C)  II, III 
D)  I, II 
E)  II, IV

Question 4

Consider the following chemical reaction at equilibrium: 2 Cl2(g) + 2 H2O(g) ⇌ 4 HCl(g) + O2(g)
This equilibrium can be shifted to the right by:

Accepted Answer

A)  removing H2O(g) from the mixture. 
B)  adding more O2(g) to the mixture. 
C)  adding Ne(g) to the mixture. 
D)  decreasing the volume of the mixture. 
E)  increasing the volume of the mixture. 
A)  removing H2O(g) from the mixture. 
B)  adding more O2(g) to the mixture. 
C)  adding Ne(g) to the mixture. 
D)  decreasing the volume of the mixture. 
E)  increasing the volume of the mixture.

Question 5

Given that the equilibrium concentrations of [N2] = 0.035 M, [C2H2] = 0.057 M, and [HCN] = 6.8 × 10-4 M, find the value of the equilibrium constant expression for the reaction:
N2(g) + C2H2(g) ⇌ 2 HCN

Accepted Answer

A)  3.4 × 10-1 
B)  2.9 
C)  4300 
D)  2.3 × 10-4 
E)  6.8 × 10-1 
A)  3.4 × 10-1 
B)  2.9 
C)  4300 
D)  2.3 × 10-4 
E)  6.8 × 10-1

Question 6

For the reaction CO(g) + 3 H2(g) ⇌ H2O(g) + CH4(g), Kc = 190 at 1000 K. If a vessel is filled with these gases such that the initial concentrations are [CO] = 0.036 M, [H2] = 0.045, [H2O] = 0.020, and [CH4] = 0.031, in which direction will a reaction occur and why?

Accepted Answer

A)  toward products because Q = 0.38 
B)  toward reactants because Q = 0.24 
C)  toward products because Q = 4.1 
D)  toward reactants because Q = 61 
E)  it is at equilibrium because Q = 1 
A)  toward products because Q = 0.38 
B)  toward reactants because Q = 0.24 
C)  toward products because Q = 4.1 
D)  toward reactants because Q = 61 
E)  it is at equilibrium because Q = 1

Question 7

In a reaction at equilibrium involving only gases, a change in pressure of the reaction mixture shifts the position of equilibrium only when:

Accepted Answer

A)  heat is absorbed by the reaction proceeding to the right 
B)  the gases are impure 
C)  the collision rate increases 
D)  the reaction is exothermic as written 
E)  the moles of gas are not equal on the two sides of the equation. 
A)  heat is absorbed by the reaction proceeding to the right 
B)  the gases are impure 
C)  the collision rate increases 
D)  the reaction is exothermic as written 
E)  the moles of gas are not equal on the two sides of the equation.

Question 8

For the reaction 2 SO2 (g) + O2 (g) ⇌ 2 SO3 (g), Kc = 2.8 × 102 at 1000 K. If a vessel is filled with these gases such that the initial concentrations are [SO2] = 0.025, [O2] = 0.035, and [SO3] = 0.046, in which direction will a reaction occur and why?

Accepted Answer

A)  toward products because Q = 53 
B)  toward reactants because Q = 0.019 
C)  toward products because Q = 96 
D)  toward reactants because Q = 2.8 × 103 
E)  it is at equilibrium because Q = 1 
A)  toward products because Q = 53 
B)  toward reactants because Q = 0.019 
C)  toward products because Q = 96 
D)  toward reactants because Q = 2.8 × 103 
E)  it is at equilibrium because Q = 1

Question 9

For the production of NO2, Kc = [NO2]2/[NO]2[O2]. At equilibrium in a 2.50 L container, there are 3.00 mol NO, 4.00 mol O2 and 22.0 mol NO2. The value of Kc is ________.

Accepted Answer

A)  13.4 
B)  33.6 
C)  5.38 
D)  0.0116 
E)  3.75 
A)  13.4 
B)  33.6 
C)  5.38 
D)  0.0116 
E)  3.75

Question 10

Consider the following reaction. C(s) + H2O(g) ⇌ CO(g) + H2(g)
At equilibrium at a certain temperature, [H2O(g)] = 0.12 M, and [CO(g)] = [H2(g)] = 1.2 M. If suddenly these concentrations are increased by 0.50 M, which of the following is true?

Accepted Answer

A)  more products are formed 
B)  Kc = 4.66 
C)  more H2O(g) will be formed 
D)  Since Kc does not change, nothing happens. 
A)  more products are formed 
B)  Kc = 4.66 
C)  more H2O(g) will be formed 
D)  Since Kc does not change, nothing happens.

Question 11

For the reaction: 3 Fe(s) + 4 H2O(g) ⇌ Fe3O4(s) + 4 H2(g)
Write the expression for Kp.

Accepted Answer

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

Question 12

Given the following: 
 I) N2O(g) + 1/2 O2(g) ⇌ 2NO(g) Kc = 1.7 × 10-13
II) N2(g) + O2(g) ⇌ 2NO(g) Kc = 4.1 × 10-31
Find the value of the equilibrium constant for the following equilibrium reaction:
N2(g) + 1/2 O2(g) ⇌ N2O(g)

Accepted Answer

A)  7.0 × 10-44 
B)  4.2 × 1017 
C)  2.4 × 10-18 
D)  1.6 × 10-9 
E)  2.6 × 10-22 
A)  7.0 × 10-44 
B)  4.2 × 1017 
C)  2.4 × 10-18 
D)  1.6 × 10-9 
E)  2.6 × 10-22

Question 13

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

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.

Question 14

Which factor influences the value of the equilibrium constant for a reversible reaction?

Accepted Answer

A)  addition of a catalyst 
B)  raising the temperature 
C)  removing product 
D)  removing reactant 
E)  increase in mixing rate 
A)  addition of a catalyst 
B)  raising the temperature 
C)  removing product 
D)  removing reactant 
E)  increase in mixing rate

Question 15

What is the value for Kc for the reaction below if the equilibrium concentrations are [N2] = 0.025, [H2] = 0.0013 and [NH3] = 0.028 for the following reaction? N2(g) + 3 H2(g) ⇌ 2 NH3(g)

Accepted Answer

A)  8.6 × 102 
B)  1.4 × 107 
C)  1.2 × 10-3 
D)  7.1 × 10-8 
E)  7.4 × 105 
A)  8.6 × 102 
B)  1.4 × 107 
C)  1.2 × 10-3 
D)  7.1 × 10-8 
E)  7.4 × 105

Question 16

For the following chemical equilibrium, Kp = 4.6 × 10-14 at 25°C, find the value of Kc for this reaction at 25°C. 2 Cl2(g) + 2 H2O(g) ⇌ 4 HCl(g) + O2(g)

Accepted Answer

A)  Kc = 1.9 × 10-15 
B)  Kc = 2.2 × 10-14 
C)  Kc = 1.1 × 10-12 
D)  Kc = 9.4 × 10-14 
E)  Kc = 4.6 × 10-14 
A)  Kc = 1.9 × 10-15 
B)  Kc = 2.2 × 10-14 
C)  Kc = 1.1 × 10-12 
D)  Kc = 9.4 × 10-14 
E)  Kc = 4.6 × 10-14

Question 17

A mixture, containing 0.0750 M HCl(g) and 0.0330 M O2(g) is allowed to come to equilibrium at 480°C. 4HCl(g) + O2(g) ⇌ 2Cl2(g) + 2H2O(g)
At equilibrium [Cl2] = 0.030 M. What is the value of Kc?

Accepted Answer

A)  1.1 × 10-3 
B)  890 
C)  0.13 
D)  1.3 
E)  480 
A)  1.1 × 10-3 
B)  890 
C)  0.13 
D)  1.3 
E)  480

Question 18

At a certain temperature, Kc = 0.0500 and △H = +39.6 kJ for the reaction below. 2MgCl2(s) + O2(g) ⇌ 2MgO(s) + 2Cl2(g)
Calculate Kc for the reaction
MgO(s) + Cl2(g) ⇌ MgCl2(s) +   O2(g)
And indicate whether the value will be larger or smaller at a lower temperature.

Accepted Answer

A)  4.47, larger 
B)  400, smaller 
C)  0.224, larger 
D)  0.224, smaller 
A)  4.47, larger 
B)  400, smaller 
C)  0.224, larger 
D)  0.224, smaller

Question 19

For the reaction: CH4(g) + 2H2O(g) ⇌ CO2(g) + 4H2(g)  &emsp; ΔH° = +190 kJ add N2(g) at constant volume and:

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. 
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.

Question 20

For the reaction: PCl3(g) + Cl2(g) ⇌ PCl5(g) at 70.5°C, Kp = 1.05.
If one starts with 1.80 atm pressure of PCl3(g), 1.72 atm pressure of Cl2(g), and no PCl5(g), what is the partial pressure of PCl5(g) at equilibrium?

Accepted Answer

A)  0.827 atm 
B)  0.856 atm 
C)  0.818 atm 
D)  0.599 atm 
E)  0.080 atm 
A)  0.827 atm 
B)  0.856 atm 
C)  0.818 atm 
D)  0.599 atm 
E)  0.080 atm

Exam 15: Principles of Chemical Equilibrium

In an equilibrium process, the concentrations of products and of reactants are equal.

Which of the following substances present in the chemical reaction would be excluded from the equilibrium constant expression?

For the reaction; N2(g) + 3 H2(g) ⇌ 2 NH3(g), the equilibrium amount of NH3 will be increased by: I. increasing the pressure II. adding H2 III. removing N2 IV. decreasing the pressure

Consider the following chemical reaction at equilibrium: 2 Cl2(g) + 2 H2O(g) ⇌ 4 HCl(g) + O2(g) This equilibrium can be shifted to the right by:

Given that the equilibrium concentrations of [N2] = 0.035 M, [C2H2] = 0.057 M, and [HCN] = 6.8 × 10-4 M, find the value of the equilibrium constant expression for the reaction: N2(g) + C2H2(g) ⇌ 2 HCN

For the reaction CO(g) + 3 H2(g) ⇌ H2O(g) + CH4(g), Kc = 190 at 1000 K. If a vessel is filled with these gases such that the initial concentrations are [CO] = 0.036 M, [H2] = 0.045, [H2O] = 0.020, and [CH4] = 0.031, in which direction will a reaction occur and why?

In a reaction at equilibrium involving only gases, a change in pressure of the reaction mixture shifts the position of equilibrium only when:

For the reaction 2 SO2 (g) + O2 (g) ⇌ 2 SO3 (g), Kc = 2.8 × 102 at 1000 K. If a vessel is filled with these gases such that the initial concentrations are [SO2] = 0.025, [O2] = 0.035, and [SO3] = 0.046, in which direction will a reaction occur and why?

For the production of NO2, Kc = [NO2]2/[NO]2[O2]. At equilibrium in a 2.50 L container, there are 3.00 mol NO, 4.00 mol O2 and 22.0 mol NO2. The value of Kc is ________.

Consider the following reaction. C(s) + H2O(g) ⇌ CO(g) + H2(g) At equilibrium at a certain temperature, [H2O(g)] = 0.12 M, and [CO(g)] = [H2(g)] = 1.2 M. If suddenly these concentrations are increased by 0.50 M, which of the following is true?

For the reaction: 3 Fe(s) + 4 H2O(g) ⇌ Fe3O4(s) + 4 H2(g) Write the expression for Kp.

Given the following: I) N2O(g) + 1/2 O2(g) ⇌ 2NO(g) Kc = 1.7 × 10-13 II) N2(g) + O2(g) ⇌ 2NO(g) Kc = 4.1 × 10-31 Find the value of the equilibrium constant for the following equilibrium reaction: N2(g) + 1/2 O2(g) ⇌ N2O(g)

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

Which factor influences the value of the equilibrium constant for a reversible reaction?

What is the value for Kc for the reaction below if the equilibrium concentrations are [N2] = 0.025, [H2] = 0.0013 and [NH3] = 0.028 for the following reaction? N2(g) + 3 H2(g) ⇌ 2 NH3(g)

For the following chemical equilibrium, Kp = 4.6 × 10-14 at 25°C, find the value of Kc for this reaction at 25°C. 2 Cl2(g) + 2 H2O(g) ⇌ 4 HCl(g) + O2(g)

A mixture, containing 0.0750 M HCl(g) and 0.0330 M O2(g) is allowed to come to equilibrium at 480°C. 4HCl(g) + O2(g) ⇌ 2Cl2(g) + 2H2O(g) At equilibrium [Cl2] = 0.030 M. What is the value of Kc?

At a certain temperature, Kc = 0.0500 and △H = +39.6 kJ for the reaction below. 2MgCl2(s) + O2(g) ⇌ 2MgO(s) + 2Cl2(g) Calculate Kc for the reaction MgO(s) + Cl2(g) ⇌ MgCl2(s) + O2(g) And indicate whether the value will be larger or smaller at a lower temperature.

For the reaction: CH4(g) + 2H2O(g) ⇌ CO2(g) + 4H2(g) ΔH° = +190 kJ add N2(g) at constant volume and:

For the reaction: PCl3(g) + Cl2(g) ⇌ PCl5(g) at 70.5°C, Kp = 1.05. If one starts with 1.80 atm pressure of PCl3(g), 1.72 atm pressure of Cl2(g), and no PCl5(g), what is the partial pressure of PCl5(g) at equilibrium?

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

For the reaction; N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g), the equilibrium amount of NH₃ will be increased by: I. increasing the pressure II. adding H₂ III. removing N₂ IV. decreasing the pressure

Consider the following chemical reaction at equilibrium: 2 Cl₂(g) + 2 H₂O(g) ⇌ 4 HCl(g) + O₂(g) This equilibrium can be shifted to the right by:

Given that the equilibrium concentrations of [N₂] = 0.035 M, [C₂H₂] = 0.057 M, and [HCN] = 6.8 × 10^-4 M, find the value of the equilibrium constant expression for the reaction: N₂(g) + C₂H₂(g) ⇌ 2 HCN

For the reaction CO(g) + 3 H₂(g) ⇌ H₂O(g) + CH₄(g), Kc = 190 at 1000 K. If a vessel is filled with these gases such that the initial concentrations are [CO] = 0.036 M, [H₂] = 0.045, [H₂O] = 0.020, and [CH₄] = 0.031, in which direction will a reaction occur and why?

For the reaction 2 SO₂ (g) + O₂ (g) ⇌ 2 SO₃ (g), Kc = 2.8 × 10² at 1000 K. If a vessel is filled with these gases such that the initial concentrations are [SO₂] = 0.025, [O₂] = 0.035, and [SO₃] = 0.046, in which direction will a reaction occur and why?

For the production of NO₂, Kc = [NO₂]₂/[NO]₂[O₂]. At equilibrium in a 2.50 L container, there are 3.00 mol NO, 4.00 mol O₂ and 22.0 mol NO₂. The value of Kc is ________.

Consider the following reaction. C(s) + H₂O(g) ⇌ CO(g) + H₂(g) At equilibrium at a certain temperature, [H₂O(g)] = 0.12 M, and [CO(g)] = [H₂(g)] = 1.2 M. If suddenly these concentrations are increased by 0.50 M, which of the following is true?

For the reaction: 3 Fe(s) + 4 H₂O(g) ⇌ Fe₃O₄(s) + 4 H₂(g) Write the expression for Kp.

Given the following: I) N₂O(g) + 1/2 O₂(g) ⇌ 2NO(g) Kc = 1.7 × 10^-13 II) N₂(g) + O₂(g) ⇌ 2NO(g) Kc = 4.1 × 10^-31 Find the value of the equilibrium constant for the following equilibrium reaction: N₂(g) + 1/2 O₂(g) ⇌ N₂O(g)

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

What is the value for Kc for the reaction below if the equilibrium concentrations are [N₂] = 0.025, [H₂] = 0.0013 and [NH₃] = 0.028 for the following reaction? N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g)

For the following chemical equilibrium, Kp = 4.6 × 10^-14 at 25°C, find the value of Kc for this reaction at 25°C. 2 Cl₂(g) + 2 H₂O(g) ⇌ 4 HCl(g) + O₂(g)

A mixture, containing 0.0750 M HCl(g) and 0.0330 M O₂(g) is allowed to come to equilibrium at 480°C. 4HCl(g) + O₂(g) ⇌ 2Cl₂(g) + 2H₂O(g) At equilibrium [Cl₂] = 0.030 M. What is the value of Kc?

At a certain temperature, Kc = 0.0500 and △H = +39.6 kJ for the reaction below. 2MgCl₂(s) + O₂(g) ⇌ 2MgO(s) + 2Cl₂(g) Calculate Kc for the reaction MgO(s) + Cl₂(g) ⇌ MgCl₂(s) + O₂(g) And indicate whether the value will be larger or smaller at a lower temperature.

For the reaction: CH₄(g) + 2H₂O(g) ⇌ CO₂(g) + 4H₂(g) ΔH° = +190 kJ add N₂(g) at constant volume and:

For the reaction: PCl₃(g) + Cl₂(g) ⇌ PCl₅(g) at 70.5°C, Kp = 1.05. If one starts with 1.80 atm pressure of PCl₃(g), 1.72 atm pressure of Cl₂(g), and no PCl₅(g), what is the partial pressure of PCl₅(g) at equilibrium?