Question 1

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 2

Cyclohexane (C6H12)undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane (MCP)according to the equation:
C6H12 ⇌ MCP
If Kc = 0.143 at 25 °C for this reaction,predict the direction in which the system will shift if the initial concentrations of C6H12 and MCP are 0.0400 mol L-1 and 0.0200 mol L-1,respectively.The system:

Accepted Answer

A) will shift left 
B) will shift right 
C) is already at equilibrium 
D) is not at equilibrium and will remain in an unequilibrated state 
A) will shift left 
B) will shift right 
C) is already at equilibrium 
D) is not at equilibrium and will remain in an unequilibrated state

Question 3

For the reaction PCl5 (g)⇌ PCl3 (g)+ Cl2 (g)Kc = 0.0454 at 261 °C.If a vessel is filled with these gases such that the initial concentrations are [PCl5] = 0.20 M,[PCl3] = 0.20 M,and [Cl2] = 2.5 M,in which direction will a reaction occur and why?

Accepted Answer

A) toward products because Qc = 0.56 
B) toward reactants because Qc = 2.5 
C) toward products because Qc = 2.8 
D) toward reactants because Qc = 0.0454 
E) it is at equilibrium because Qc = 1 
A) toward products because Qc = 0.56 
B) toward reactants because Qc = 2.5 
C) toward products because Qc = 2.8 
D) toward reactants because Qc = 0.0454 
E) it is at equilibrium because Qc = 1

Question 4

Given the following reactions,
2 PCl3(g)⇌ 2 P(g)+ 3 Cl2(g)Kc = 0.0667
PCl3(g)+ Cl2(g)⇌ PCl5(g)Kc = 4.0
Calculate Kc for the reaction below.
2 P(g)+ 5 Cl2(g)⇌ 2 PCl5(g)

Accepted Answer

A) 240 
B) 1.1 
C) 60 
D) 23 
E) 0.41 
A) 240 
B) 1.1 
C) 60 
D) 23 
E) 0.41

Question 5

Find Kp for the following reaction at 25.0 °C.
SbCl5(g)⇌ SbCl3(g)+ Cl2(g)Kc = 2.51 × 10-2

Accepted Answer

A) 0.614 
B) 1.03 × 10-3  
C) 5.15 × 10-2  
D) 9.74 × 102  
E) 39.8 
A) 0.614 
B) 1.03 × 10-3  
C) 5.15 × 10-2  
D) 9.74 × 102  
E) 39.8

Question 6

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

Question 7

What is the equilibrium constant expression for:
4 NH3(g)+ 5 O2(g)⇌ 4 NO(g)+ 6 H2O(g)

Accepted Answer

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

Question 8

For the isomerization reaction:
Butane ⇌ isobutane
Kp equals 25.0 at 500 °C.If the initial pressures of butane and isobutane are 20.0 atm and 0.0 atm,respectively,what are the pressures of the two gases at equilibrium?

Accepted Answer

A) P(butane)= 0.77 atm and P(isobutane)= 19.2 atm 
B) P(butane)= 0.80 atm and P(isobutane)= 20.atm 
C) P(butane)= 19.2 atm and P(isobutane)= 0.77 atm 
D) P(butane)= 20 atm and P(isobutane)= 0.80 atm 
A) P(butane)= 0.77 atm and P(isobutane)= 19.2 atm 
B) P(butane)= 0.80 atm and P(isobutane)= 20.atm 
C) P(butane)= 19.2 atm and P(isobutane)= 0.77 atm 
D) P(butane)= 20 atm and P(isobutane)= 0.80 atm

Question 9

Consider the reaction:
CH4(g)+ 4 Cl2(g)⇌ CCl4(l)+ 4 HCl(g),ΔrH° = -398 kJ/mol
The equilibrium is displaced to the right if:

Accepted Answer

A) the temperature is raised 
B) the pressure is lowered 
C) some carbon tetrachloride is removed 
D) some hydrogen chloride is added 
E) some chlorine gas is removed 
A) the temperature is raised 
B) the pressure is lowered 
C) some carbon tetrachloride is removed 
D) some hydrogen chloride is added 
E) some chlorine gas is removed

Question 10

The concentration of a pure solid is left out of a equilibrium constant expression but a pure liquid is included.

Accepted Answer

A) True 
 B)False

Question 11

Two moles of NH3 are initially present for the reaction:
2 NH3(g)⇌ N2(g)+ 3 H2(g)
At equilibrium there is 1.00 mol NH3.How many moles of H2 are present at equilibrium?

Accepted Answer

A) 3.00 moles 
B) 1.00 moles 
C) 1.50 moles 
D) 0.67 moles 
E) 0.75 moles 
A) 3.00 moles 
B) 1.00 moles 
C) 1.50 moles 
D) 0.67 moles 
E) 0.75 moles

Question 12

Phosphorus trichloride and phosphorus pentachloride equilibrate in the presence of molecular chlorine according to the following reaction: 
  (g)+   (g)→   (g)
An equilibrium mixture at 450 K contains   = 0.124 bar,   = 0.157 bar,and   = 1.30 bar.
What is the value of Kp at this temperature?

Accepted Answer

A) 66.8 
B) 1.50 ×   
C) 2.53 × 10-2 
D) 1.02 
E) 4.63 
A) 66.8 
B) 1.50 ×   
C) 2.53 × 10-2 
D) 1.02 
E) 4.63

Question 13

A mixture containing 0.0392 M A(g)and 0.0452 M B(g)is allowed to come to equilibrium at 300 K.The reaction: 3 A(g)+ 2 B(g)⇌ C(g)+ D(g)occurs.At equilibrium,[C] = 0.00128 M.What is the value of Kc?

Accepted Answer

A) 2.13 × 10-3  
B) 0.849 
C) 20.4 
D) 4.91 × 10-2  
E) 470 
A) 2.13 × 10-3  
B) 0.849 
C) 20.4 
D) 4.91 × 10-2  
E) 470

Question 14

For the reaction 2 NO2(g)⇌ N2O4(g)Kp equals ________.

Accepted Answer

A) Kc  
B) RT/Kc  
C) Kc(RT) 
D) Kc/RT 
E) Kc(RT)2 
A) Kc  
B) RT/Kc  
C) Kc(RT) 
D) Kc/RT 
E) Kc(RT)2

Question 15

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 M,[O2] = 0.035 M,and [SO3] = 0.046 M,in which direction will a reaction occur and why?

Accepted Answer

A) toward products because Qc = 53 
B) toward reactants because Qc = 0.019 
C) toward products because Qc = 97 
D) toward reactants because Qc = 2.8 × 103  
E) it is at equilibrium because Qc = 1 
A) toward products because Qc = 53 
B) toward reactants because Qc = 0.019 
C) toward products because Qc = 97 
D) toward reactants because Qc = 2.8 × 103  
E) it is at equilibrium because Qc = 1

Question 16

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the equation:

At 250 °C 0.125 mol L-1 PCl5 is added to the flask.If Kc = 1.80,what are the equilibrium concentrations of each gas?

Accepted Answer

A) [PCl5] = 0.00765 mol L-1,[PCl3] = 0.117 mol L-1,and [Cl2] = 0.117 mol L-1 
B) [PCl5] = 0.0625 mol L-1,[PCl3] = 0.335 mol L-1,and [Cl2] = 0.335 mol L-1 
C) [PCl5] = 1.80 mol L-1,[PCl3] = 1.80 mol L-1,and [Cl2] = 1.80 mol L-1 
D) [PCl5] = 3.96 mol L-1,[PCl3] = 3.83 mol L-1,and [Cl2] = 3.83 mol L-1 
A) [PCl5] = 0.00765 mol L-1,[PCl3] = 0.117 mol L-1,and [Cl2] = 0.117 mol L-1 
B) [PCl5] = 0.0625 mol L-1,[PCl3] = 0.335 mol L-1,and [Cl2] = 0.335 mol L-1 
C) [PCl5] = 1.80 mol L-1,[PCl3] = 1.80 mol L-1,and [Cl2] = 1.80 mol L-1 
D) [PCl5] = 3.96 mol L-1,[PCl3] = 3.83 mol L-1,and [Cl2] = 3.83 mol L-1

Question 17

For the reaction: N2(g)+ 2 O2(g)⇌ 2 NO2(g),Kc = 8.3 × 10-10 M-1 at 25 °C.What is the concentration of N2 gas at equilibrium when the concentration of NO2 is five times the concentration of O2 gas?

Accepted Answer

A) 3.3 × 10-11 mol L-1 
B) 1.7 × 10-10 mol L-1 
C) 6.0 × 109 mol L-1 
D) 3.0 × 1010 mol L-1 
A) 3.3 × 10-11 mol L-1 
B) 1.7 × 10-10 mol L-1 
C) 6.0 × 109 mol L-1 
D) 3.0 × 1010 mol L-1

Question 18

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 19

The value of the equilibrium constant for a given reaction depends on the initial concentrations of reactants.

Accepted Answer

A) True 
 B)False

Question 20

0.75 mol of N2 and 1.20 mol of H2 are placed in a 3.0 liter container.When the reaction
N2(g)+ 3 H2(g)⇌ 2 NH3(g)reaches equilibrium,[H2] = 0.100 M.Which of the following is true?

Accepted Answer

A) [NH3] = 0.150 M 
B) [NH3] = 0.200 M 
C) [N2] = 0.650 M 
D) [N2] = 0.250 M 
E) [NH3] = [H2] = 0.05 M 
A) [NH3] = 0.150 M 
B) [NH3] = 0.200 M 
C) [N2] = 0.650 M 
D) [N2] = 0.250 M 
E) [NH3] = [H2] = 0.05 M

Exam 15: Principles of Chemical Equilibrium

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

For the reaction PCl5 (g)⇌ PCl3 (g)+ Cl2 (g)Kc = 0.0454 at 261 °C.If a vessel is filled with these gases such that the initial concentrations are [PCl5] = 0.20 M,[PCl3] = 0.20 M,and [Cl2] = 2.5 M,in which direction will a reaction occur and why?

Given the following reactions, 2 PCl3(g)⇌ 2 P(g)+ 3 Cl2(g)Kc = 0.0667 PCl3(g)+ Cl2(g)⇌ PCl5(g)Kc = 4.0 Calculate Kc for the reaction below. 2 P(g)+ 5 Cl2(g)⇌ 2 PCl5(g)

Find Kp for the following reaction at 25.0 °C. SbCl5(g)⇌ SbCl3(g)+ Cl2(g)Kc = 2.51 × 10-2

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 equilibrium constant expression for: 4 NH3(g)+ 5 O2(g)⇌ 4 NO(g)+ 6 H2O(g)

For the isomerization reaction: Butane ⇌ isobutane Kp equals 25.0 at 500 °C.If the initial pressures of butane and isobutane are 20.0 atm and 0.0 atm,respectively,what are the pressures of the two gases at equilibrium?

Consider the reaction: CH4(g)+ 4 Cl2(g)⇌ CCl4(l)+ 4 HCl(g),ΔrH° = -398 kJ/mol The equilibrium is displaced to the right if:

The concentration of a pure solid is left out of a equilibrium constant expression but a pure liquid is included.

Two moles of NH3 are initially present for the reaction: 2 NH3(g)⇌ N2(g)+ 3 H2(g) At equilibrium there is 1.00 mol NH3.How many moles of H2 are present at equilibrium?

Phosphorus trichloride and phosphorus pentachloride equilibrate in the presence of molecular chlorine according to the following reaction: (g)+ (g)→ (g) An equilibrium mixture at 450 K contains = 0.124 bar, = 0.157 bar,and = 1.30 bar. What is the value of Kp at this temperature?

A mixture containing 0.0392 M A(g)and 0.0452 M B(g)is allowed to come to equilibrium at 300 K.The reaction: 3 A(g)+ 2 B(g)⇌ C(g)+ D(g)occurs.At equilibrium,[C] = 0.00128 M.What is the value of Kc?

For the reaction 2 NO2(g)⇌ N2O4(g)Kp equals ________.

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 M,[O2] = 0.035 M,and [SO3] = 0.046 M,in which direction will a reaction occur and why?

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the equation: At 250 °C 0.125 mol L-1 PCl5 is added to the flask.If Kc = 1.80,what are the equilibrium concentrations of each gas?

For the reaction: N2(g)+ 2 O2(g)⇌ 2 NO2(g),Kc = 8.3 × 10-10 M-1 at 25 °C.What is the concentration of N2 gas at equilibrium when the concentration of NO2 is five times the concentration of O2 gas?

Equilibrium constant K is constant except when one varies the:

The value of the equilibrium constant for a given reaction depends on the initial concentrations of reactants.

0.75 mol of N2 and 1.20 mol of H2 are placed in a 3.0 liter container.When the reaction N2(g)+ 3 H2(g)⇌ 2 NH3(g)reaches equilibrium,[H2] = 0.100 M.Which of the following is true?

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: Valence Bond and Molecular Orbital Theories

Intermolecular Forces: Liquids and Solids

Spontaneous Change: Entropy and Gibbs Energy

Solutions and Their Physical Properties

Acids and Bases

Additional Aspects of Acidbase Equilibria

Solubility and Complex-Ion Equilibria

Electrochemistry

Chemical Kinetics

Chemistry of the Main-Group Elements I: Groups 1,2,13,and 14

Chemistry of the Main-Group Elements Ii: Groups 18,17,16,15,and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry

Structures of Organic Compounds

Reactions of Organic Compounds

Chemistry of the Living State

Filters

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

For the reaction PCl₅ (g)⇌ PCl₃ (g)+ Cl₂ (g)K_c = 0.0454 at 261 °C.If a vessel is filled with these gases such that the initial concentrations are [PCl₅] = 0.20 M,[PCl₃] = 0.20 M,and [Cl₂] = 2.5 M,in which direction will a reaction occur and why?

Given the following reactions, 2 PCl₃(g)⇌ 2 P(g)+ 3 Cl₂(g)K_c = 0.0667 PCl₃(g)+ Cl₂(g)⇌ PCl₅(g)K_c = 4.0 Calculate K_c for the reaction below. 2 P(g)+ 5 Cl₂(g)⇌ 2 PCl₅(g)

Find K_p for the following reaction at 25.0 °C. SbCl₅(g)⇌ SbCl₃(g)+ Cl₂(g)K_c = 2.51 × 10^-2

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 equilibrium constant expression for: 4 NH₃(g)+ 5 O₂(g)⇌ 4 NO(g)+ 6 H₂O(g)

For the isomerization reaction: Butane ⇌ isobutane K_p equals 25.0 at 500 °C.If the initial pressures of butane and isobutane are 20.0 atm and 0.0 atm,respectively,what are the pressures of the two gases at equilibrium?

Consider the reaction: CH₄(g)+ 4 Cl₂(g)⇌ CCl₄(l)+ 4 HCl(g),Δ_rH° = -398 kJ/mol The equilibrium is displaced to the right if:

Two moles of NH₃ are initially present for the reaction: 2 NH₃(g)⇌ N₂(g)+ 3 H₂(g) At equilibrium there is 1.00 mol NH₃.How many moles of H₂ are present at equilibrium?

Phosphorus trichloride and phosphorus pentachloride equilibrate in the presence of molecular chlorine according to the following reaction: (g)+ (g)→ (g) An equilibrium mixture at 450 K contains = 0.124 bar, = 0.157 bar,and = 1.30 bar. What is the value of K_p at this temperature?

A mixture containing 0.0392 M A(g)and 0.0452 M B(g)is allowed to come to equilibrium at 300 K.The reaction: 3 A(g)+ 2 B(g)⇌ C(g)+ D(g)occurs.At equilibrium,[C] = 0.00128 M.What is the value of K_c?

For the reaction 2 NO₂(g)⇌ N₂O₄(g)K_p equals ________.

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

Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the equation: At 250 °C 0.125 mol L^-1 PCl₅ is added to the flask.If K_c = 1.80,what are the equilibrium concentrations of each gas?

For the reaction: N₂(g)+ 2 O₂(g)⇌ 2 NO₂(g),K_c = 8.3 × 10^-10 M^-1at 25 °C.What is the concentration of N₂ gas at equilibrium when the concentration of NO₂ is five times the concentration of O₂ gas?

0.75 mol of N₂ and 1.20 mol of H₂ are placed in a 3.0 liter container.When the reaction N₂(g)+ 3 H₂(g)⇌ 2 NH₃(g)reaches equilibrium,[H₂] = 0.100 M.Which of the following is true?