Question 1

Which statement is correct?

Accepted Answer

A) If Q  K,then reactants must be converted to products. 
C) If Q = K,then the system is at equilibrium. 
D) If Q < K,then more reactants are produced. 
E) None of the answers is correct. 
A) If Q  K,then reactants must be converted to products. 
C) If Q = K,then the system is at equilibrium. 
D) If Q < K,then more reactants are produced. 
E) None of the answers is correct.

Question 2

The observation that at equilibrium,the reaction quotient equals the equilibrium constant,is representative of which law?

Accepted Answer

A) Law of equal states 
B) Reversibility law 
C) Law of equivalence 
D) Law of reactant-product equivalence 
E) Law of mass action 
A) Law of equal states 
B) Reversibility law 
C) Law of equivalence 
D) Law of reactant-product equivalence 
E) Law of mass action

Question 3

Consider this reaction at equilibrium at a total pressure: 2H2O(g)+ O2(g)   2H2O2(g)
Suppose the volume of this system is twice its initial volume and then equilibrium is reestablished.The new equilibrium total pressure will be

Accepted Answer

A) more than half the total initial pressure. 
B) twice the total pressure. 
C) less than half the total initial pressure. 
D) unchanged. 
E) exactly one half of the initial total pressure. 
A) more than half the total initial pressure. 
B) twice the total pressure. 
C) less than half the total initial pressure. 
D) unchanged. 
E) exactly one half of the initial total pressure.

Question 4

At 1500°C the equilibrium constant for the reaction CO(g)+ 2H2(g)   CH3OH(g)has the value KP = 1.4 × 10-7.What is ΔG° for this reaction at 1500°C? (R = 8.314 J/K • mol)

Accepted Answer

A) 105 kJ/mol 
B) 1.07 kJ/mol 
C) -233 kJ/mol 
D) -105 kJ/mol 
E) 233 kJ/mol 
A) 105 kJ/mol 
B) 1.07 kJ/mol 
C) -233 kJ/mol 
D) -105 kJ/mol 
E) 233 kJ/mol

Question 5

Which represents the correct relationship between the Gibbs free energy and the equilibrium constant?

Accepted Answer

A) ΔG = -RT lnK 
B) ΔG = RT lnK 
C) ΔGo = -RT lnK 
D) ΔGo = -RT lnQ 
E) ΔGo = RT lnQ 
A) ΔG = -RT lnK 
B) ΔG = RT lnK 
C) ΔGo = -RT lnK 
D) ΔGo = -RT lnQ 
E) ΔGo = RT lnQ

Question 6

For any reaction,if ΔG° > 0,then K < 1.

Accepted Answer

A) True 
 B)False

Question 7

A change in a concentration will not change the position of equilibrium.

Accepted Answer

A) True 
 B)False

Question 8

Sodium carbonate,Na2CO3(s),may be prepared by heating sodium bicarbonate,NaHCO3(s). 2NaHCO3(s)   Na2CO3(s)+ CO2(g)+ H2O(g)KP = 0.23 at 100ºC
If a sample of NaHCO3 is placed in an evacuated flask and allowed to achieve equilibrium at 100ºC,what will the total gas pressure be?

Accepted Answer

A) 0.46 atm 
B) 0.96 atm 
C) 0.23 atm 
D) 0.48 atm 
E) 0.11 atm 
A) 0.46 atm 
B) 0.96 atm 
C) 0.23 atm 
D) 0.48 atm 
E) 0.11 atm

Question 9

For the following reaction at equilibrium in a reaction vessel,which one of these changes would cause the I2 concentration to increase? 2NOI(g)   2NO(g)+ I2(g),ΔHºrxn = 45.3 kJ/mol

Accepted Answer

A) Add some NO 
B) Expand the gas mixture into a larger volume 
C) Decrease the temperature 
D) Increase the system pressure 
E) Remove some NOI 
A) Add some NO 
B) Expand the gas mixture into a larger volume 
C) Decrease the temperature 
D) Increase the system pressure 
E) Remove some NOI

Question 10

The equilibrium constant expression for the reaction
CuO(s)+ H2(g)   Cu(s)+ H2O(g)is Kc = [H2]/[H2O].

Accepted Answer

A) True 
 B)False

Question 11

What is the free energy change,ΔG°,for the equilibrium between hydrogen iodide,hydrogen, and iodine at 453°C? (R = 8.314 J/K• mol)
2HI(g)   H2(g)+ I2(g)Kc = 0.020 at T = 453°C

Accepted Answer

A) 6.4 kJ/mol 
B) 8.8 kJ/mol 
C) 15 kJ/mol 
D) 19 kJ/mol 
E) 24 kJ/mol 
A) 6.4 kJ/mol 
B) 8.8 kJ/mol 
C) 15 kJ/mol 
D) 19 kJ/mol 
E) 24 kJ/mol

Question 12

Solid ammonium hydrogen sulfide is introduced into a 2.00-L flask,and the flask is sealed.If this solid decomposes according to the equation NH4HS(s)   NH3(g)+ H2S(g),KP = 0.108 at 25°C,what is the minimum mass of ammonium hydrogen sulfide that must be present in the flask initially if equilibrium is to be established at 25°C? (R = 0.08206 L • atm/K • mol)

Accepted Answer

A) 0.917 g 
B) 1.37 g 
C) 2.74 g 
D) 0.581 g 
E) 0.452 g 
A) 0.917 g 
B) 1.37 g 
C) 2.74 g 
D) 0.581 g 
E) 0.452 g

Question 13

For the equilibrium A2(g)   2A(g),if a sample of A2(g)is placed in a sealed container and allowed to come to equilibrium,which graph best represents the relationship between Kc and time as equilibrium is established?

Accepted Answer

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

Question 14

Increasing the temperature of an exothermic reaction causes the equilibrium constant to increase and shifts the equilibrium toward products.

Accepted Answer

A) True 
 B)False

Question 15

Which of the following is the expression that relates Kc to KP?

Accepted Answer

A) Kc = KP R/T 
B) KP = Kc(RT)Δn 
C) KP = Kc/(RT)Δn 
D) Kc KP = RT/V 
E) KP = KcP/RT 
A) Kc = KP R/T 
B) KP = Kc(RT)Δn 
C) KP = Kc/(RT)Δn 
D) Kc KP = RT/V 
E) KP = KcP/RT

Question 16

For the reaction 2X(g)+ Y(g)   2Z(g),Kc = 1.00 ×103 at 500 K.If at equilibrium the concentration of X is 0.20 M and the concentration of Y is 0.50 M,what is the equilibrium concentration of Z?

Accepted Answer

A) 2.2 M 
B) 3.2 M 
C) 3.5 M 
D) 4.5 M 
E) 7.1 M 
A) 2.2 M 
B) 3.2 M 
C) 3.5 M 
D) 4.5 M 
E) 7.1 M

Question 17

For the endothermic reaction A2 (g)   2A(g),a snapshot of an equilibrium mixture of A(g) and A2 (g)at low temperature may look as follows.(Each circle represents 1.0 mol of A atoms,and the volume of the box is 1.0 L.)   If the temperature is raised,what might the new equilibrium system look like?

Accepted Answer

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

Question 18

Stearic acid,nature's most common fatty acid,dimerizes when dissolved in hexane: 2C17H35COOH   (C17H35COOH)2; ΔH°rxn = -172 kJ/mol
The equilibrium constant for this reaction at 28°C is 2.9 × 103.Estimate the equilibrium constant at 38°C.(R = 8.314 J/K• mol)

Accepted Answer

A) 4.7 × 105 
B) 2.6 × 104 
C) 1.9 × 103 
D) 3.2 × 102 
E) 18 
A) 4.7 × 105 
B) 2.6 × 104 
C) 1.9 × 103 
D) 3.2 × 102 
E) 18

Question 19

At a certain temperature the reaction CO2(g)+ H2(g)   CO(g)+ H2O(g)
Has Kc = 2.50.If 2.00 mol of carbon dioxide and 1.50 mol of hydrogen are placed in a 5.00-L vessel and equilibrium is established,what is the equilibrium concentration of carbon monoxide?

Accepted Answer

A) 0.209 M 
B) 1.33 M 
C) 0.267 M 
D) 0.667 M 
E) 0.600 M 
A) 0.209 M 
B) 1.33 M 
C) 0.267 M 
D) 0.667 M 
E) 0.600 M

Question 20

At 850°C,the equilibrium constant,KP,for the reaction C(s)+ CO2(g)   2CO(g)has a value of 10.7
If the total pressure in the system at equilibrium is 1.000 atm,what is the partial pressure of carbon monoxide at equilibrium?

Accepted Answer

A) 0.362 atm 
B) 0.489 atm 
C) 0.667 atm 
D) 0.915 atm 
E) 0.921 atm 
A) 0.362 atm 
B) 0.489 atm 
C) 0.667 atm 
D) 0.915 atm 
E) 0.921 atm

Exam 15: Chemical Equilibrium

Which statement is correct?

The observation that at equilibrium,the reaction quotient equals the equilibrium constant,is representative of which law?

Consider this reaction at equilibrium at a total pressure: 2H2O(g)+ O2(g) 2H2O2(g) Suppose the volume of this system is twice its initial volume and then equilibrium is reestablished.The new equilibrium total pressure will be

At 1500°C the equilibrium constant for the reaction CO(g)+ 2H2(g) CH3OH(g)has the value KP = 1.4 × 10-7.What is ΔG° for this reaction at 1500°C? (R = 8.314 J/K • mol)

Which represents the correct relationship between the Gibbs free energy and the equilibrium constant?

For any reaction,if ΔG° > 0,then K < 1.

A change in a concentration will not change the position of equilibrium.

Sodium carbonate,Na2CO3(s),may be prepared by heating sodium bicarbonate,NaHCO3(s). 2NaHCO3(s) Na2CO3(s)+ CO2(g)+ H2O(g)KP = 0.23 at 100ºC If a sample of NaHCO3 is placed in an evacuated flask and allowed to achieve equilibrium at 100ºC,what will the total gas pressure be?

For the following reaction at equilibrium in a reaction vessel,which one of these changes would cause the I2 concentration to increase? 2NOI(g) 2NO(g)+ I2(g),ΔHºrxn = 45.3 kJ/mol

The equilibrium constant expression for the reaction CuO(s)+ H2(g) Cu(s)+ H2O(g)is Kc = [H2]/[H2O].

What is the free energy change,ΔG°,for the equilibrium between hydrogen iodide,hydrogen, and iodine at 453°C? (R = 8.314 J/K• mol) 2HI(g) H2(g)+ I2(g)Kc = 0.020 at T = 453°C

For the equilibrium A2(g) 2A(g),if a sample of A2(g)is placed in a sealed container and allowed to come to equilibrium,which graph best represents the relationship between Kc and time as equilibrium is established?

Increasing the temperature of an exothermic reaction causes the equilibrium constant to increase and shifts the equilibrium toward products.

Which of the following is the expression that relates Kc to KP?

For the reaction 2X(g)+ Y(g) 2Z(g),Kc = 1.00 ×103 at 500 K.If at equilibrium the concentration of X is 0.20 M and the concentration of Y is 0.50 M,what is the equilibrium concentration of Z?

For the endothermic reaction A2 (g) 2A(g),a snapshot of an equilibrium mixture of A(g) and A2 (g)at low temperature may look as follows.(Each circle represents 1.0 mol of A atoms,and the volume of the box is 1.0 L.) If the temperature is raised,what might the new equilibrium system look like?

Stearic acid,nature's most common fatty acid,dimerizes when dissolved in hexane: 2C17H35COOH (C17H35COOH)2; ΔH°rxn = -172 kJ/mol The equilibrium constant for this reaction at 28°C is 2.9 × 103.Estimate the equilibrium constant at 38°C.(R = 8.314 J/K• mol)

At a certain temperature the reaction CO2(g)+ H2(g) CO(g)+ H2O(g) Has Kc = 2.50.If 2.00 mol of carbon dioxide and 1.50 mol of hydrogen are placed in a 5.00-L vessel and equilibrium is established,what is the equilibrium concentration of carbon monoxide?

At 850°C,the equilibrium constant,KP,for the reaction C(s)+ CO2(g) 2CO(g)has a value of 10.7 If the total pressure in the system at equilibrium is 1.000 atm,what is the partial pressure of carbon monoxide at equilibrium?

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Consider this reaction at equilibrium at a total pressure: 2H₂O(g)+ O₂(g) 2H₂O₂(g) Suppose the volume of this system is twice its initial volume and then equilibrium is reestablished.The new equilibrium total pressure will be

At 1500°C the equilibrium constant for the reaction CO(g)+ 2H₂(g) CH₃OH(g)has the value K_P = 1.4 × 10^-7.What is ΔG° for this reaction at 1500°C? (R = 8.314 J/K • mol)

Sodium carbonate,Na₂CO₃(s),may be prepared by heating sodium bicarbonate,NaHCO₃(s). 2NaHCO₃(s) Na₂CO₃(s)+ CO₂(g)+ H₂O(g)K_P = 0.23 at 100ºC If a sample of NaHCO₃ is placed in an evacuated flask and allowed to achieve equilibrium at 100ºC,what will the total gas pressure be?

For the following reaction at equilibrium in a reaction vessel,which one of these changes would cause the I₂ concentration to increase? 2NOI(g) 2NO(g)+ I₂(g),ΔHº_rxn = 45.3 kJ/mol

The equilibrium constant expression for the reaction CuO(s)+ H₂(g) Cu(s)+ H₂O(g)is K_c = [H₂]/[H₂O].

What is the free energy change,ΔG°,for the equilibrium between hydrogen iodide,hydrogen, and iodine at 453°C? (R = 8.314 J/K• mol) 2HI(g) H₂(g)+ I₂(g)K_c = 0.020 at T = 453°C

For the equilibrium A₂(g) 2A(g),if a sample of A₂(g)is placed in a sealed container and allowed to come to equilibrium,which graph best represents the relationship between K_c and time as equilibrium is established?

Which of the following is the expression that relates K_c to K_P?

For the reaction 2X(g)+ Y(g) 2Z(g),Kc = 1.00 ×10³ at 500 K.If at equilibrium the concentration of X is 0.20 M and the concentration of Y is 0.50 M,what is the equilibrium concentration of Z?

For the endothermic reaction A₂ (g) 2A(g),a snapshot of an equilibrium mixture of A(g) and A₂ (g)at low temperature may look as follows.(Each circle represents 1.0 mol of A atoms,and the volume of the box is 1.0 L.) If the temperature is raised,what might the new equilibrium system look like?

Stearic acid,nature's most common fatty acid,dimerizes when dissolved in hexane: 2C₁₇H₃₅COOH (C₁₇H₃₅COOH)₂; ΔH°_rxn = -172 kJ/mol The equilibrium constant for this reaction at 28°C is 2.9 × 10³.Estimate the equilibrium constant at 38°C.(R = 8.314 J/K• mol)

At a certain temperature the reaction CO₂(g)+ H₂(g) CO(g)+ H₂O(g) Has K_c = 2.50.If 2.00 mol of carbon dioxide and 1.50 mol of hydrogen are placed in a 5.00-L vessel and equilibrium is established,what is the equilibrium concentration of carbon monoxide?

At 850°C,the equilibrium constant,K_P,for the reaction C(s)+ CO₂(g) 2CO(g)has a value of 10.7 If the total pressure in the system at equilibrium is 1.000 atm,what is the partial pressure of carbon monoxide at equilibrium?