Question 1

Which of the following expressions is the correct equilibrium-constant expression for the reaction below? (NH4)2Se (s)   2NH3 (g)+ H2Se (g)

Accepted Answer

A) [NH3][H2Se] / [(NH4)2Se] 
B) [(NH4)2Se] / [NH3]2[H2Se] 
C) 1 / [(NH4)2Se] 
D) [NH3]2[H2Se] 
E) [NH3]2[H2Se] / [(NH4)2Se] 
A) [NH3][H2Se] / [(NH4)2Se] 
B) [(NH4)2Se] / [NH3]2[H2Se] 
C) 1 / [(NH4)2Se] 
D) [NH3]2[H2Se] 
E) [NH3]2[H2Se] / [(NH4)2Se]

Question 2

At 200°C, the equilibrium constant (Kp)for the reaction below is 2.40 × 103. 2NO (g)   N2 (g)+ O2 (g)
A closed vessel is charged with 36.1 atm of NO. At equilibrium, the partial pressure of O2 is __________ atm.

Accepted Answer

A) 294 
B) 35.7 
C) 17.9 
D) 6.00 
E) 1.50 × 10-2 
A) 294 
B) 35.7 
C) 17.9 
D) 6.00 
E) 1.50 × 10-2

Question 3

The effect of a catalyst on an equilibrium is to __________.

Accepted Answer

A) increase the rate of the forward reaction only 
B) increase the equilibrium constant so that products are favored 
C) slow the reverse reaction only 
D) increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture 
E) shift the equilibrium to the right 
A) increase the rate of the forward reaction only 
B) increase the equilibrium constant so that products are favored 
C) slow the reverse reaction only 
D) increase the rate at which equilibrium is achieved without changing the composition of the equilibrium mixture 
E) shift the equilibrium to the right

Question 4

Given the following reaction at equilibrium, if Kc = 6.34 x 105 at 230.0°C, Kp = __________. 2NO (g)+ O2 (g)   2NO2 (g)

Accepted Answer

A) 3.67 × 10-2 
B) 1.53 × 104 
C) 6.44 × 105 
D) 2.61 × 106 
E) 2.62 × 107 
A) 3.67 × 10-2 
B) 1.53 × 104 
C) 6.44 × 105 
D) 2.61 × 106 
E) 2.62 × 107

Question 5

The value of Keq for the equilibrium H2 (g)+ I2 (g)   2 HI (g)
Is 794 at 25°C. At this temperature, what is the value of Keq for the equilibrium below?
HI (g)   1/2 H2 (g)+ 1/2 I2 (g)

Accepted Answer

A) 1588 
B) 28 
C) 397 
D) 0.035 
E) 0.0013 
A) 1588 
B) 28 
C) 397 
D) 0.035 
E) 0.0013

Question 6

A sealed 1.0 L flask is charged with 0.500 mol of I2 and 0.500 mol of Br2. An equilibrium reaction ensues: I2 (g)+ Br2 (g)   2IBr (g)
When the container contents achieve equilibrium, the flask contains 0.84 mol of IBr. The value of Keq is __________.

Accepted Answer

A) 11 
B) 4.0 
C) 110 
D) 6.1 
E) 2.8 
A) 11 
B) 4.0 
C) 110 
D) 6.1 
E) 2.8

Question 7

The equilibrium expression for Kp for the reaction below is __________. N2 (g)+ O2 (g)   2NO (g)

Accepted Answer

A)    
B)    
C)    
D)    
E) none of the above 
A)    
B)    
C)    
D)    
E) none of the above

Question 8

The Kp for the reaction below is 1.49 × 108 at 100.0°C: CO (g)+ Cl2 (g)   COCl2 (g)
In an equilibrium mixture of the three gases, PCO = PCl2 = 2.22 × 10-4 atm. The partial pressure of the product, phosgene (COCl2), is __________ atm.

Accepted Answer

A) 7.34 
B) 3.02 × 1015 
C) 3.31 × 10-16 
D) 3.31 × 104 
E) 6.67 × 1011 
A) 7.34 
B) 3.02 × 1015 
C) 3.31 × 10-16 
D) 3.31 × 104 
E) 6.67 × 1011

Question 9

The value of Keq for the equilibrium H2 (g)+ I2 (g)   2 HI (g)
Is 794 at 25 °C. What is the value of Keq for the equilibrium below?
1/2 H2 (g)+ 1/2 I2 (g)   HI (g)

Accepted Answer

A) 397 
B) 0.035 
C) 28 
D) 1588 
E) 0.0013 
A) 397 
B) 0.035 
C) 28 
D) 1588 
E) 0.0013

Question 10

At 400 K, the equilibrium constant for the reaction Br2 (g)+ Cl2 (g)   2BrCl (g)
Is Kp = 7.0. A closed vessel at 400 K is charged with 1.00 atm of Br2 (g), 1.00 atm of Cl2 (g), and 2.00 atm of BrCl (g). Use Q to determine which of the statements below is true.

Accepted Answer

A) The equilibrium partial pressures of Br2, Cl2, and BrCl will be the same as the initial values. 
B) The equilibrium partial pressure of Br2 will be greater than 1.00 atm. 
C) At equilibrium, the total pressure in the vessel will be less than the initial total pressure. 
D) The equilibrium partial pressure of BrCl (g)will be greater than 2.00 atm. 
E) The reaction will go to completion since there are equal amounts of Br2 and Cl2. 
A) The equilibrium partial pressures of Br2, Cl2, and BrCl will be the same as the initial values. 
B) The equilibrium partial pressure of Br2 will be greater than 1.00 atm. 
C) At equilibrium, the total pressure in the vessel will be less than the initial total pressure. 
D) The equilibrium partial pressure of BrCl (g)will be greater than 2.00 atm. 
E) The reaction will go to completion since there are equal amounts of Br2 and Cl2.

Question 11

Consider the following equilibrium. 2SO2 (g)+ O2 (g)   2SO3 (g)
The equilibrium cannot be established when __________ is/are placed in a 1.0-L container.

Accepted Answer

A) 0.25 mol SO2 (g)and 0.25 mol O2 (g) 
B) 0.75 mol SO2 (g) 
C) 0.25 mol of SO2 (g)and 0.25 mol of SO3 (g) 
D) 0.50 mol O2 (g)and 0.50 mol SO3 (g) 
E) 1.0 mol SO3 (g) 
A) 0.25 mol SO2 (g)and 0.25 mol O2 (g) 
B) 0.75 mol SO2 (g) 
C) 0.25 mol of SO2 (g)and 0.25 mol of SO3 (g) 
D) 0.50 mol O2 (g)and 0.50 mol SO3 (g) 
E) 1.0 mol SO3 (g)

Question 12

Given the following reaction: CO (g)+ 2H2(g)   CH3OH (g)
In an experiment, 0.42 mol of CO and 0.42 mol of H2 were placed in a 1.00-L reaction vessel. At equilibrium, there were 0.29 mol of CO remaining. Keq at the temperature of the experiment is __________.

Accepted Answer

A) 2.80 
B) 0.357 
C) 14.5 
D) 17.5 
E) none of the above 
A) 2.80 
B) 0.357 
C) 14.5 
D) 17.5 
E) none of the above

Question 13

At 900.0 K, the equilibrium constant (Kp)for the following reaction is 0.345. 2SO2 + O2 (g)   2SO3 (g)
At equilibrium, the partial pressure of SO2 is 35.0 atm and that of O2 is 15.9 atm. The partial pressure of SO3 is __________ atm.

Accepted Answer

A) 82.0 
B) 4.21 × 10-3 
C) 192 
D) 6.20 × 10-4 
E) 40.2 
A) 82.0 
B) 4.21 × 10-3 
C) 192 
D) 6.20 × 10-4 
E) 40.2

Question 14

Of the following equilibria, only __________ will shift to the right in response to a decrease in volume.

Accepted Answer

A) H2 (g)+ Cl2 (g)   2 HCl (g) 
B) 2 SO3 (g)   2 SO2 (g)+ O2 (g) 
C) N2 (g)+ 3 H2 (g)   2 NH3 (g) 
D) 2 Fe2O3 (s)   4 Fe (s)+ 3 O2 (g) 
E) 2HI (g)   H2 (g)+ I2 (g) 
A) H2 (g)+ Cl2 (g)   2 HCl (g) 
B) 2 SO3 (g)   2 SO2 (g)+ O2 (g) 
C) N2 (g)+ 3 H2 (g)   2 NH3 (g) 
D) 2 Fe2O3 (s)   4 Fe (s)+ 3 O2 (g) 
E) 2HI (g)   H2 (g)+ I2 (g)

Question 15

If the value for the equilibrium constant is much greater than 1, then the equilibrium mixture contains mostly __________.

Accepted Answer

The answer of If the value for the equilibrium constant...

Question 16

Given the following reaction at equilibrium, if Kp = 0.990 at 250.0°C, Kc = __________. PCl5 (g)   PCl3 (g)+ Cl2 (g)

Accepted Answer

A) 3.90 × 10-6 
B) 2.31 × 10-2 
C) 0.990 
D) 42.9 
E) 42.5 
A) 3.90 × 10-6 
B) 2.31 × 10-2 
C) 0.990 
D) 42.9 
E) 42.5

Question 17

Which of the following statements is true?

Accepted Answer

A) Q does not change with temperature. 
B) Keq does not change with temperature, whereas Q is temperature dependent. 
C) K does not depend on the concentrations or partial pressures of reaction components. 
D) Q does not depend on the concentrations or partial pressures of reaction components. 
E) Q is the same as Keq when a reaction is at equilibrium. 
A) Q does not change with temperature. 
B) Keq does not change with temperature, whereas Q is temperature dependent. 
C) K does not depend on the concentrations or partial pressures of reaction components. 
D) Q does not depend on the concentrations or partial pressures of reaction components. 
E) Q is the same as Keq when a reaction is at equilibrium.

Question 18

Consider the following reaction at equilibrium: 2NH3 (g)   N2 (g)+ 3H2 (g)ΔH° = +92.4 kJ
Le Châtelier's principle predicts that adding N2 (g)to the system at equilibrium will result in __________.

Accepted Answer

A) a decrease in the concentration of NH3 (g) 
B) a decrease in the concentration of H2 (g) 
C) an increase in the value of the equilibrium constant 
D) a lower partial pressure of N2 
E) removal of all of the H2 (g) 
A) a decrease in the concentration of NH3 (g) 
B) a decrease in the concentration of H2 (g) 
C) an increase in the value of the equilibrium constant 
D) a lower partial pressure of N2 
E) removal of all of the H2 (g)

Question 19

The equilibrium constant for the gas phase reaction 2SO2 (g)+ O2 (g)   2SO3 (g)
Is Keq = 2.80 × 102 at 999 K. At equilibrium, __________.

Accepted Answer

A) products predominate 
B) reactants predominate 
C) roughly equal amounts of products and reactants are present 
D) only products are present 
E) only reactants are present 
A) products predominate 
B) reactants predominate 
C) roughly equal amounts of products and reactants are present 
D) only products are present 
E) only reactants are present

Question 20

Consider the following reaction at equilibrium: 2NH3 (g)   N2 (g)+ 3H2 (g)
Le Châtelier's principle predicts that the moles of H2 in the reaction container will increase with __________.

Accepted Answer

A) some removal of NH3 from the reaction vessel (V and T constant) 
B) a decrease in the total pressure (T constant) 
C) addition of some N2 to the reaction vessel (V and T constant) 
D) a decrease in the total volume of the reaction vessel (T constant) 
E) an increase in total pressure by the addition of helium gas (V and T constant) 
A) some removal of NH3 from the reaction vessel (V and T constant) 
B) a decrease in the total pressure (T constant) 
C) addition of some N2 to the reaction vessel (V and T constant) 
D) a decrease in the total volume of the reaction vessel (T constant) 
E) an increase in total pressure by the addition of helium gas (V and T constant)

Exam 15: Chemical Equilibrium

Which of the following expressions is the correct equilibrium-constant expression for the reaction below? (NH4)2Se (s) 2NH3 (g)+ H2Se (g)

At 200°C, the equilibrium constant (Kp)for the reaction below is 2.40 × 103. 2NO (g) N2 (g)+ O2 (g) A closed vessel is charged with 36.1 atm of NO. At equilibrium, the partial pressure of O2 is __________ atm.

The effect of a catalyst on an equilibrium is to __________.

Given the following reaction at equilibrium, if Kc = 6.34 x 105 at 230.0°C, Kp = __________. 2NO (g)+ O2 (g) 2NO2 (g)

The value of Keq for the equilibrium H2 (g)+ I2 (g) 2 HI (g) Is 794 at 25°C. At this temperature, what is the value of Keq for the equilibrium below? HI (g) 1/2 H2 (g)+ 1/2 I2 (g)

A sealed 1.0 L flask is charged with 0.500 mol of I2 and 0.500 mol of Br2. An equilibrium reaction ensues: I2 (g)+ Br2 (g) 2IBr (g) When the container contents achieve equilibrium, the flask contains 0.84 mol of IBr. The value of Keq is __________.

The equilibrium expression for Kp for the reaction below is __________. N2 (g)+ O2 (g) 2NO (g)

The Kp for the reaction below is 1.49 × 108 at 100.0°C: CO (g)+ Cl2 (g) COCl2 (g) In an equilibrium mixture of the three gases, PCO = PCl2 = 2.22 × 10-4 atm. The partial pressure of the product, phosgene (COCl2), is __________ atm.

The value of Keq for the equilibrium H2 (g)+ I2 (g) 2 HI (g) Is 794 at 25 °C. What is the value of Keq for the equilibrium below? 1/2 H2 (g)+ 1/2 I2 (g) HI (g)

At 400 K, the equilibrium constant for the reaction Br2 (g)+ Cl2 (g) 2BrCl (g) Is Kp = 7.0. A closed vessel at 400 K is charged with 1.00 atm of Br2 (g), 1.00 atm of Cl2 (g), and 2.00 atm of BrCl (g). Use Q to determine which of the statements below is true.

Consider the following equilibrium. 2SO2 (g)+ O2 (g) 2SO3 (g) The equilibrium cannot be established when __________ is/are placed in a 1.0-L container.

Given the following reaction: CO (g)+ 2H2(g) CH3OH (g) In an experiment, 0.42 mol of CO and 0.42 mol of H2 were placed in a 1.00-L reaction vessel. At equilibrium, there were 0.29 mol of CO remaining. Keq at the temperature of the experiment is __________.

At 900.0 K, the equilibrium constant (Kp)for the following reaction is 0.345. 2SO2 + O2 (g) 2SO3 (g) At equilibrium, the partial pressure of SO2 is 35.0 atm and that of O2 is 15.9 atm. The partial pressure of SO3 is __________ atm.

Of the following equilibria, only __________ will shift to the right in response to a decrease in volume.

If the value for the equilibrium constant is much greater than 1, then the equilibrium mixture contains mostly __________.

Given the following reaction at equilibrium, if Kp = 0.990 at 250.0°C, Kc = __________. PCl5 (g) PCl3 (g)+ Cl2 (g)

Which of the following statements is true?

Consider the following reaction at equilibrium: 2NH3 (g) N2 (g)+ 3H2 (g)ΔH° = +92.4 kJ Le Châtelier's principle predicts that adding N2 (g)to the system at equilibrium will result in __________.

The equilibrium constant for the gas phase reaction 2SO2 (g)+ O2 (g) 2SO3 (g) Is Keq = 2.80 × 102 at 999 K. At equilibrium, __________.

Consider the following reaction at equilibrium: 2NH3 (g) N2 (g)+ 3H2 (g) Le Châtelier's principle predicts that the moles of H2 in the reaction container will increase with __________.

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Which of the following expressions is the correct equilibrium-constant expression for the reaction below? (NH₄)₂Se (s) 2NH₃ (g)+ H₂Se (g)

At 200°C, the equilibrium constant (K_p)for the reaction below is 2.40 × 10³. 2NO (g) N₂ (g)+ O₂ (g) A closed vessel is charged with 36.1 atm of NO. At equilibrium, the partial pressure of O₂ is __________ atm.

Given the following reaction at equilibrium, if K_c = 6.34 x 10⁵at 230.0°C, K_p = __________. 2NO (g)+ O₂ (g) 2NO₂ (g)

The value of K_eq for the equilibrium H₂ (g)+ I₂ (g) 2 HI (g) Is 794 at 25°C. At this temperature, what is the value of K_e_q for the equilibrium below? HI (g) 1/2 H₂ (g)+ 1/2 I₂ (g)

A sealed 1.0 L flask is charged with 0.500 mol of I₂ and 0.500 mol of Br₂. An equilibrium reaction ensues: I₂ (g)+ Br₂ (g) 2IBr (g) When the container contents achieve equilibrium, the flask contains 0.84 mol of IBr. The value of K_eq is __________.

The equilibrium expression for K_p for the reaction below is __________. N₂ (g)+ O₂ (g) 2NO (g)

The K_p for the reaction below is 1.49 × 10⁸ at 100.0°C: CO (g)+ Cl₂ (g) COCl₂ (g) In an equilibrium mixture of the three gases, PCO = PCl₂ = 2.22 × 10^-4 atm. The partial pressure of the product, phosgene (COCl₂), is __________ atm.

The value of K_eq for the equilibrium H₂ (g)+ I₂ (g) 2 HI (g) Is 794 at 25 °C. What is the value of K_eq for the equilibrium below? 1/2 H₂ (g)+ 1/2 I₂ (g) HI (g)

At 400 K, the equilibrium constant for the reaction Br₂ (g)+ Cl₂ (g) 2BrCl (g) Is K_p = 7.0. A closed vessel at 400 K is charged with 1.00 atm of Br₂(g), 1.00 atm of Cl₂ (g), and 2.00 atm of BrCl (g). Use Q to determine which of the statements below is true.

Consider the following equilibrium. 2SO₂ (g)+ O₂ (g) 2SO₃ (g) The equilibrium cannot be established when __________ is/are placed in a 1.0-L container.

Given the following reaction: CO (g)+ 2H₂(g) CH₃OH (g) In an experiment, 0.42 mol of CO and 0.42 mol of H₂ were placed in a 1.00-L reaction vessel. At equilibrium, there were 0.29 mol of CO remaining. K_eq at the temperature of the experiment is __________.

At 900.0 K, the equilibrium constant (K_p)for the following reaction is 0.345. 2SO₂ + O₂ (g) 2SO₃ (g) At equilibrium, the partial pressure of SO₂ is 35.0 atm and that of O₂ is 15.9 atm. The partial pressure of SO₃ is __________ atm.

Given the following reaction at equilibrium, if K_p = 0.990 at 250.0°C, K_c = __________. PCl₅ (g) PCl₃ (g)+ Cl₂ (g)

Consider the following reaction at equilibrium: 2NH₃ (g) N₂ (g)+ 3H₂ (g)ΔH° = +92.4 kJ Le Châtelier's principle predicts that adding N₂ (g)to the system at equilibrium will result in __________.

The equilibrium constant for the gas phase reaction 2SO₂ (g)+ O₂ (g) 2SO₃ (g) Is K_eq = 2.80 × 10² at 999 K. At equilibrium, __________.

Consider the following reaction at equilibrium: 2NH₃ (g) N₂ (g)+ 3H₂ (g) Le Châtelier's principle predicts that the moles of H₂ in the reaction container will increase with __________.