Question 1

For which of the following equilibria does Kc = Kp?

Accepted Answer

A) N2(g)+ 3H2(g)   2NH3(g) 
B) CO(g)+ H2O(g)   CO2(g)+ H2(g) 
C) CO(g)+ 3H2(g)   CH4(g)+ H2O(g) 
D) CaO(s)+ CO2(g)   CaCO3(s) 
E) HBr(g)   1/2H2(g)+ 1/2Br2(l) 
A) N2(g)+ 3H2(g)   2NH3(g) 
B) CO(g)+ H2O(g)   CO2(g)+ H2(g) 
C) CO(g)+ 3H2(g)   CH4(g)+ H2O(g) 
D) CaO(s)+ CO2(g)   CaCO3(s) 
E) HBr(g)   1/2H2(g)+ 1/2Br2(l)

Question 2

Given the equilibrium constants for the following reactions:
4Cu(s)+ O2(g)  
2Cu2O(s); K1
2CuO(s)  
Cu2O(s) + ½ O2(g); K2
What is K for the system
2Cu(s)+ O2(g)  
2CuO(s)
Equivalent to?

Accepted Answer

A) (K2)2/(K1) 
B) K1 × K2 
C) (K1)(K2)1/2 
D) (K2)½/(K1) 
E) (K1)1/2/(K2) 
A) (K2)2/(K1) 
B) K1 × K2 
C) (K1)(K2)1/2 
D) (K2)½/(K1) 
E) (K1)1/2/(K2)

Question 3

Sulfur dioxide combines with O2 in the presence of a catalyst as represented by the equation
2SO2(g)+ O2(g)  
2SO3(g)
Suppose 0.10 mol of SO2 and 0.10 mol of O2 are added to a 1-L vessel.At equilibrium,which of the following conditions must be true?

Accepted Answer

A) [O2] = 2[SO3] 
B) [SO2] = [O2] 
C) [SO2] > [O2] 
D) [SO2] 2] 
E) [SO2] = [O2] = [SO3] 
A) [O2] = 2[SO3] 
B) [SO2] = [O2] 
C) [SO2] > [O2] 
D) [SO2] 2] 
E) [SO2] = [O2] = [SO3]

Question 4

The following reaction is investigated (assume an ideal gas mixture):
2N2O(g)+ N2H4(g)  
3N2(g)+ 2H2O(g)
Initially there are 0.100 mol of N2O and 0.25 mol of N2H4,in a 10.0-L container.If there are 0.059 mol of N2O at equilibrium,how many moles of N2 are present at equilibrium?

Accepted Answer

A) 4.1 × 10-2 
B) 1.2 × 10-1 
C) 6.2 × 10-2 
D) 2.1 × 10-2 
E) none of these 
A) 4.1 × 10-2 
B) 1.2 × 10-1 
C) 6.2 × 10-2 
D) 2.1 × 10-2 
E) none of these

Question 5

Carbon monoxide is toxic because it can successfully compete with oxygen for hemoglobin (Hb)sites according to the following equilibrium:
Hb(O2)4(aq)+ 4CO(g)  
Hb(CO)4(aq)+ 4O2(g)
From Le Châtelier's principle,CO poisoning is reversed by

Accepted Answer

A) increasing the O2 pressure. 
B) decreasing the amount of Hb. 
C) increasing the CO2 pressure. 
D) increasing the CO pressure. 
E) increasing the amount of Hb. 
A) increasing the O2 pressure. 
B) decreasing the amount of Hb. 
C) increasing the CO2 pressure. 
D) increasing the CO pressure. 
E) increasing the amount of Hb.

Question 6

Which of the following represents a dynamic equilibrium?

Accepted Answer

A) a stoppered flask half full of water 
B) a coin spinning in mid-air 
C) two people of equal mass balanced on the ends of a seesaw 
D) an open pan of boiling water 
E) an object traveling at a constant speed 
A) a stoppered flask half full of water 
B) a coin spinning in mid-air 
C) two people of equal mass balanced on the ends of a seesaw 
D) an open pan of boiling water 
E) an object traveling at a constant speed

Question 7

In which of the following reactions does a decrease in the volume of the reaction vessel at constant temperature favor formation of the products?

Accepted Answer

A) 2H2(g)+ O2(g)   2H2O(g) 
B) NO2(g)+ CO(g)   NO(g)+ CO2(g) 
C) H2(g)+ I2(g)   2HI(g) 
D) 2O3(g)   3O2(g) 
E) MgCO3(s)   MgO(s)+ CO2(g) 
A) 2H2(g)+ O2(g)   2H2O(g) 
B) NO2(g)+ CO(g)   NO(g)+ CO2(g) 
C) H2(g)+ I2(g)   2HI(g) 
D) 2O3(g)   3O2(g) 
E) MgCO3(s)   MgO(s)+ CO2(g)

Question 8

The equilibrium constant for the reaction H2(g)+ I2(g)   2HI(g)is 62.5 at 800 K.What is the equilibrium concentration of I2 if at equilibrium [HI] = 0.21 M and [H2] = 0.13 M?

Accepted Answer

A) 5.4 × 10-3 M 
B) 0.29 M 
C) 5.2 × 10-2 M 
D) 0.21 M 
E) 2.6 × 10-2 M 
A) 5.4 × 10-3 M 
B) 0.29 M 
C) 5.2 × 10-2 M 
D) 0.21 M 
E) 2.6 × 10-2 M

Question 9

_____ states that,when a system in chemical equilibrium is disturbed by a change of temperature,pressure,or a concentration,the system shifts in equilibrium composition in a way that tends to counteract this change of variable.

Accepted Answer

A) ​Bernoulli's principle 
B) ​Le Châtelier's principle 
C) ​Fermat's principle 
D) ​Heisenberg's uncertainty principle 
E) ​The Pauli exclusion principle 
A) ​Bernoulli's principle 
B) ​Le Châtelier's principle 
C) ​Fermat's principle 
D) ​Heisenberg's uncertainty principle 
E) ​The Pauli exclusion principle

Question 10

Which of the following correctly describes the equilibrium constant for the gas-phase reaction between H2 and O2 to form gaseous H2O?

Accepted Answer

A) Kc =   
B) Kc =   
C) Kc = [H2O] 
D) Kc =   
E) Kc =   
A) Kc =   
B) Kc =   
C) Kc = [H2O] 
D) Kc =   
E) Kc =

Question 11

Apply the law of mass action to obtain the equilibrium-constant expression for the following reaction:
2X(g)+ Y(g)  
3W(g)+ V(g)

Accepted Answer

A) [X]2[Y][W]3[V] 
B)    
C)    
D)    
A) [X]2[Y][W]3[V] 
B)    
C)    
D)

Question 12

Consider the following equilibrium:
PCl5(g)  
PCl3(g)+ Cl2 (g); ΔH = 92 kJ
The concentration of PCl3 at equilibrium may be increased by

Accepted Answer

A) decreasing the temperature. 
B) adding Cl2 to the system. 
C) adding PCl5 to the system. 
D) increasing the pressure. 
E) adding a catalyst. 
A) decreasing the temperature. 
B) adding Cl2 to the system. 
C) adding PCl5 to the system. 
D) increasing the pressure. 
E) adding a catalyst.

Question 13

Which of the following is the main step in the contact process for the industrial production of sulfuric acid?

Accepted Answer

A) ​Oxidation of SO2 in the presence of a catalyst 
B) ​Oxidation of SO3 in the presence of a catalyst 
C) ​Oxidation of SO in the presence of a catalyst 
D) ​Reduction of SO2 in the presence of a catalyst 
E) ​Reduction of SO4 in the presence of a catalyst 
A) ​Oxidation of SO2 in the presence of a catalyst 
B) ​Oxidation of SO3 in the presence of a catalyst 
C) ​Oxidation of SO in the presence of a catalyst 
D) ​Reduction of SO2 in the presence of a catalyst 
E) ​Reduction of SO4 in the presence of a catalyst

Question 14

Consider the following equilibrium:
2NH3(g)  
N2(g)+ 3H2(g); ΔH = 92 kJ
What change should be made in order to increase the value of Kp for this reaction?

Accepted Answer

A) Increase the pressure. 
B) Decrease the temperature. 
C) Increase the temperature. 
D) Decrease the pressure. 
E) Nothing; Kp cannot be changed. 
A) Increase the pressure. 
B) Decrease the temperature. 
C) Increase the temperature. 
D) Decrease the pressure. 
E) Nothing; Kp cannot be changed.

Question 15

Consider the following equilibrium:
C2H6(g)+ C5H12(g)  
CH4(g)+ C6H14(g); Kp = 9.57 at 500 K
Suppose 13.3 g each of CH4,C2H6,C5H12,and C6H14 are placed in a 50.0-L reaction vessel at 500 K.What is the value of Qp?

Accepted Answer

A) 1 
B) 0.104 
C) 1.56 
D) 0.637 
E) 9.57 
A) 1 
B) 0.104 
C) 1.56 
D) 0.637 
E) 9.57

Question 16

At 700 K,Kp for the following equilibrium is 5.6 × 10-3.
2HgO(s)  
2Hg(l)+ O2(g)
Suppose 72.2 g of mercury(II)oxide is placed in a sealed 1.00-L vessel at 700 K.What is the partial pressure of oxygen gas at equilibrium? (R = 0.0821 L ∙ atm/(K ∙ mol))

Accepted Answer

A) 0.074 atm 
B) 0.0056 atm 
C) 19 atm 
D) 57 atm 
E) 9.5 atm 
A) 0.074 atm 
B) 0.0056 atm 
C) 19 atm 
D) 57 atm 
E) 9.5 atm

Question 17

Ammonia is prepared industrially by the reaction
N2(g)+ 3H2(g)  
2NH3(g)
For the reaction,ΔH° = -92.2 kJ and K (at 25°C)= 4.0 × 108.When the temperature of the reaction is increased to 500°C,which of the following statements is true?

Accepted Answer

A) At equilibrium,more NH3 is present at 500°C than at 25°C. 
B) The reaction of N2 with H2 to form ammonia is endothermic. 
C) K for the reaction will be larger at 500°C than at 25°C. 
D) Product formation (at equilibrium)is less favored as the temperature is raised. 
E) None of the above statements is true. 
A) At equilibrium,more NH3 is present at 500°C than at 25°C. 
B) The reaction of N2 with H2 to form ammonia is endothermic. 
C) K for the reaction will be larger at 500°C than at 25°C. 
D) Product formation (at equilibrium)is less favored as the temperature is raised. 
E) None of the above statements is true.

Question 18

Hydrogen iodide undergoes decomposition according to the equation
2HI(g)  
H2(g)+ I2(g)
The equilibrium constant Kp at 500 K for this equilibrium is 0.060.Suppose 0.811 mol of HI is placed in a 1.50-L container at 500 K.What is the equilibrium concentration of H2(g)?
(R = 0.0821 L ∙ atm/(K ∙ mol))

Accepted Answer

A) 0.21 M 
B) 0.13 M 
C) 4.3 M 
D) 0.039 M 
E) 0.1 M 
A) 0.21 M 
B) 0.13 M 
C) 4.3 M 
D) 0.039 M 
E) 0.1 M

Question 19

Consider the following equilibrium:
N2O4(g)  
2NO2(g)
Suppose two different experiments were conducted on this equilibrium,at two different temperatures.
Trial
Temperature
Initial Moles of N2O4
Equilibrium Moles of N2O4
1
25°C
1)00
0)815
2
55°C
1)00
0)500
What conclusion may be drawn from the above data?

Accepted Answer

A) Kc > Kp at all temperatures. 
B) The reaction is exothermic. 
C) The forward reaction proceeds faster than the reverse reaction. 
D) Kp = 1 at 55°C. 
E) The equilibrium constant increases with increasing temperature. 
A) Kc > Kp at all temperatures. 
B) The reaction is exothermic. 
C) The forward reaction proceeds faster than the reverse reaction. 
D) Kp = 1 at 55°C. 
E) The equilibrium constant increases with increasing temperature.

Question 20

Consider the following equilibrium:
2NO(g)+ 3F2(g)  
2NOF3(g)
Suppose 0.20 mol of NO and 0.30 mol of F2 are added to a 5.0-L container.If x mol of NOF3 is present at equilibrium,what is the equilibrium concentration of NO?

Accepted Answer

A) 0.20x 
B) 0.05 - 0.50x 
C) 0.20 - 2x 
D) 0.04 - 0.20x 
E) 0.20 - x 
A) 0.20x 
B) 0.05 - 0.50x 
C) 0.20 - 2x 
D) 0.04 - 0.20x 
E) 0.20 - x

Exam 14: Chemical Equilibrium

For which of the following equilibria does Kc = Kp?

Given the equilibrium constants for the following reactions: 4Cu(s)+ O2(g) 2Cu2O(s); K1 2CuO(s) Cu2O(s) + ½ O2(g); K2 What is K for the system 2Cu(s)+ O2(g) 2CuO(s) Equivalent to?

Sulfur dioxide combines with O2 in the presence of a catalyst as represented by the equation 2SO2(g)+ O2(g) 2SO3(g) Suppose 0.10 mol of SO2 and 0.10 mol of O2 are added to a 1-L vessel.At equilibrium,which of the following conditions must be true?

The following reaction is investigated (assume an ideal gas mixture): 2N2O(g)+ N2H4(g) 3N2(g)+ 2H2O(g) Initially there are 0.100 mol of N2O and 0.25 mol of N2H4,in a 10.0-L container.If there are 0.059 mol of N2O at equilibrium,how many moles of N2 are present at equilibrium?

Carbon monoxide is toxic because it can successfully compete with oxygen for hemoglobin (Hb)sites according to the following equilibrium: Hb(O2)4(aq)+ 4CO(g) Hb(CO)4(aq)+ 4O2(g) From Le Châtelier's principle,CO poisoning is reversed by

Which of the following represents a dynamic equilibrium?

In which of the following reactions does a decrease in the volume of the reaction vessel at constant temperature favor formation of the products?

The equilibrium constant for the reaction H2(g)+ I2(g) 2HI(g)is 62.5 at 800 K.What is the equilibrium concentration of I2 if at equilibrium [HI] = 0.21 M and [H2] = 0.13 M?

_____ states that,when a system in chemical equilibrium is disturbed by a change of temperature,pressure,or a concentration,the system shifts in equilibrium composition in a way that tends to counteract this change of variable.

Which of the following correctly describes the equilibrium constant for the gas-phase reaction between H2 and O2 to form gaseous H2O?

Apply the law of mass action to obtain the equilibrium-constant expression for the following reaction: 2X(g)+ Y(g) 3W(g)+ V(g)

Consider the following equilibrium: PCl5(g) PCl3(g)+ Cl2 (g); ΔH = 92 kJ The concentration of PCl3 at equilibrium may be increased by

Which of the following is the main step in the contact process for the industrial production of sulfuric acid?

Consider the following equilibrium: 2NH3(g) N2(g)+ 3H2(g); ΔH = 92 kJ What change should be made in order to increase the value of Kp for this reaction?

Consider the following equilibrium: C2H6(g)+ C5H12(g) CH4(g)+ C6H14(g); Kp = 9.57 at 500 K Suppose 13.3 g each of CH4,C2H6,C5H12,and C6H14 are placed in a 50.0-L reaction vessel at 500 K.What is the value of Qp?

At 700 K,Kp for the following equilibrium is 5.6 × 10-3. 2HgO(s) 2Hg(l)+ O2(g) Suppose 72.2 g of mercury(II)oxide is placed in a sealed 1.00-L vessel at 700 K.What is the partial pressure of oxygen gas at equilibrium? (R = 0.0821 L ∙ atm/(K ∙ mol))

Ammonia is prepared industrially by the reaction N2(g)+ 3H2(g) 2NH3(g) For the reaction,ΔH° = -92.2 kJ and K (at 25°C)= 4.0 × 108.When the temperature of the reaction is increased to 500°C,which of the following statements is true?

Consider the following equilibrium: 2NO(g)+ 3F2(g) 2NOF3(g) Suppose 0.20 mol of NO and 0.30 mol of F2 are added to a 5.0-L container.If x mol of NOF3 is present at equilibrium,what is the equilibrium concentration of NO?

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For which of the following equilibria does K_c = K_p?

Given the equilibrium constants for the following reactions: 4Cu(s)+ O₂(g) 2Cu₂O(s); K₁ 2CuO(s) Cu₂O(s)+ ½ O₂(g); K₂ What is K for the system 2Cu(s)+ O₂(g) 2CuO(s) Equivalent to?

Sulfur dioxide combines with O₂ in the presence of a catalyst as represented by the equation 2SO₂(g)+ O₂(g) 2SO₃(g) Suppose 0.10 mol of SO₂ and 0.10 mol of O₂ are added to a 1-L vessel.At equilibrium,which of the following conditions must be true?

The following reaction is investigated (assume an ideal gas mixture): 2N₂O(g)+ N₂H₄(g) 3N₂(g)+ 2H₂O(g) Initially there are 0.100 mol of N₂O and 0.25 mol of N₂H₄,in a 10.0-L container.If there are 0.059 mol of N₂O at equilibrium,how many moles of N₂ are present at equilibrium?

Carbon monoxide is toxic because it can successfully compete with oxygen for hemoglobin (Hb)sites according to the following equilibrium: Hb(O₂)₄(aq)+ 4CO(g) Hb(CO)₄(aq)+ 4O₂(g) From Le Châtelier's principle,CO poisoning is reversed by

The equilibrium constant for the reaction H₂(g)+ I₂(g) 2HI(g)is 62.5 at 800 K.What is the equilibrium concentration of I₂ if at equilibrium [HI] = 0.21 M and [H₂] = 0.13 M?

Which of the following correctly describes the equilibrium constant for the gas-phase reaction between H₂ and O₂ to form gaseous H₂O?

Consider the following equilibrium: PCl₅(g) PCl₃(g)+ Cl₂ (g); ΔH = 92 kJ The concentration of PCl₃ at equilibrium may be increased by

Consider the following equilibrium: 2NH₃(g) N₂(g)+ 3H₂(g); ΔH = 92 kJ What change should be made in order to increase the value of K_p for this reaction?

Consider the following equilibrium: C₂H₆(g)+ C₅H₁₂(g) CH₄(g)+ C₆H₁₄(g); K_p = 9.57 at 500 K Suppose 13.3 g each of CH₄,C₂H₆,C₅H₁₂,and C₆H₁₄ are placed in a 50.0-L reaction vessel at 500 K.What is the value of Q_p?

At 700 K,K_p for the following equilibrium is 5.6 × 10^-3. 2HgO(s) 2Hg(l)+ O₂(g) Suppose 72.2 g of mercury(II)oxide is placed in a sealed 1.00-L vessel at 700 K.What is the partial pressure of oxygen gas at equilibrium? (R = 0.0821 L ∙ atm/(K ∙ mol))

Ammonia is prepared industrially by the reaction N₂(g)+ 3H₂(g) 2NH₃(g) For the reaction,ΔH° = -92.2 kJ and K (at 25°C)= 4.0 × 10⁸.When the temperature of the reaction is increased to 500°C,which of the following statements is true?

Consider the following equilibrium: 2NO(g)+ 3F₂(g) 2NOF₃(g) Suppose 0.20 mol of NO and 0.30 mol of F₂ are added to a 5.0-L container.If x mol of NOF₃ is present at equilibrium,what is the equilibrium concentration of NO?