Question 1

Why aren't solids or liquids included in an equilibrium expression?

Accepted Answer

The equilibrium constant relates different concentrations of reactants and products to one another.Since the concentrations of liquids and solids are constant,their concentration(s)becomes part of the constant value of the equilibrium constant.

Question 2

Phosphorous trichloride and phosphorous pentachloride equilibrate in the presence of molecular chlorine according to the reaction:
PCl3(g)+ Cl2(g)⇌ PCl5(g)
An equilibrium mixture at 450 K contains
PPCl3 = 0.124 atm,
PCl2 = 0.157 atm,and
PPCl5 = 1.30 atm.What is the value of Kp at this temperature?

Accepted Answer

A) 66.7 
B) 1.50 × 10-2 
C) 2.53 × 10-2 
D) 1.02 
E) 4.63 
A) 66.7 
B) 1.50 × 10-2 
C) 2.53 × 10-2 
D) 1.02 
E) 4.63 A

Question 3

Consider the following reaction,equilibrium concentrations,and equilibrium constant at a particular temperature.Determine the equilibrium concentration of SO3(g).
2 SO2(g)+ O2(g)⇌ 2 SO3(g)Kc = 1.7 × 108
[SO2]eq = 0.0034 M [O2]eq = 0.0018 M

Accepted Answer

A) 1.9 M 
B) 1.0 × 103 M 
C) 0.53 M 
D) 9.6 × 10-4 M 
E) 0.73 M 
A) 1.9 M 
B) 1.0 × 103 M 
C) 0.53 M 
D) 9.6 × 10-4 M 
E) 0.73 M A

Question 4

Consider the following reaction at equilibrium.What effect will adding water have on the system?
CO2(g)+ 2 H2O(l)⇌ CH4(g)+ 2 O2(g)ΔH° = +890 kJ

Accepted Answer

A) The reaction will shift to the left in the direction of reactants. 
B) The equilibrium constant will decrease. 
C) The equilibrium constant will increase. 
D) The reaction will shift to the right in the direction of products. 
E) No effect will be observed. 
A) The reaction will shift to the left in the direction of reactants. 
B) The equilibrium constant will decrease. 
C) The equilibrium constant will increase. 
D) The reaction will shift to the right in the direction of products. 
E) No effect will be observed.

Question 5

The reaction below has a Kc value of 1.0 × 1012.What is the value of Kp for this reaction at 500 K?
2 SO2(g)+ O2(g)⇌ 2 SO3(g)

Accepted Answer

A) 4.2 × 10-11 
B) 1.0 × 1012 
C) 2.4 × 10-12 
D) 4.1 × 1013 
E) 2.4 × 1010 
A) 4.2 × 10-11 
B) 1.0 × 1012 
C) 2.4 × 10-12 
D) 4.1 × 1013 
E) 2.4 × 1010

Question 6

The equilibrium constant for the reaction A(g)LB(g)is 102.A reaction mixture initially contains
[A] = 10.1 M and [B] = 0.0 M.Which statement is true at equilibrium?

Accepted Answer

A) The reaction mixture contains [A] = 10.0 M and [B] = 0.10 M. 
B) The reaction mixture contains [A] = 0.10 M and [B] = 10.0 M. 
C) The reaction mixture contains [A] = 0.55 M and [B] = 0.55 M. 
D) The reaction mixture contains [A] = 1.0 M and [B] = 100.0 M. 
A) The reaction mixture contains [A] = 10.0 M and [B] = 0.10 M. 
B) The reaction mixture contains [A] = 0.10 M and [B] = 10.0 M. 
C) The reaction mixture contains [A] = 0.55 M and [B] = 0.55 M. 
D) The reaction mixture contains [A] = 1.0 M and [B] = 100.0 M.

Question 7

For the reaction: N2(g)+ 2 O2(g)⇌ 2 NO2(g),Kc = 8.3 × 10-10 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 M 
B) 1.7 × 10-10 M 
C) 6.0 × 109 M 
D) 3.0 × 1010 M 
A) 3.3 × 10-11 M 
B) 1.7 × 10-10 M 
C) 6.0 × 109 M 
D) 3.0 × 1010 M

Question 8

Consider the following reaction,equilibrium concentrations,and equilibrium constant at a particular temperature.Determine the equilibrium concentration of H2O(g).
C2H4(g)+ H2O(g)⇌ C2H5OH(g)Kc = 9.0 × 103
[C2H4]eq = 0.015 M [C2H5OH]eq = 1.69 M

Accepted Answer

A) 9.9 × 10-7 M 
B) 80.M 
C) 1.0 M 
D) 1.68 M 
E) 0.013 M 
A) 9.9 × 10-7 M 
B) 80.M 
C) 1.0 M 
D) 1.68 M 
E) 0.013 M

Question 9

The equilibrium constant is given for one of the reactions below.Determine the value of the missing equilibrium constant.
2 SO2(g)+ O2(g)⇌ 2 SO3(g)Kc = 1.7 × 106
SO3(g)⇌ 1/2 O2(g)+ SO2(g)Kc = ?

Accepted Answer

A) 3.4 × 102 
B) 8.5 
C) 1.3 × 103 
D) 1.2 × 10-6 
E) 7.7 × 10-4 
A) 3.4 × 102 
B) 8.5 
C) 1.3 × 103 
D) 1.2 × 10-6 
E) 7.7 × 10-4

Question 10

Match the following.
-Q >> 1

Accepted Answer

A) Reaction will favor formation of reactants. 
B) Reaction does not strongly favor reactants or products. 
C) Reaction favors formation of more products. 
D) Reaction has a larger amount of products than reactants. 
E) Reaction is at equilibrium. 
A) Reaction will favor formation of reactants. 
B) Reaction does not strongly favor reactants or products. 
C) Reaction favors formation of more products. 
D) Reaction has a larger amount of products than reactants. 
E) Reaction is at equilibrium.

Question 11

Match the following.
-K << 1

Accepted Answer

A) Reaction will favor formation of reactants. 
B) Reaction does not strongly favor reactants or products. 
C) Reaction favors formation of more products. 
D) Reaction has a larger amount of products than reactants. 
E) Reaction is at equilibrium. 
A) Reaction will favor formation of reactants. 
B) Reaction does not strongly favor reactants or products. 
C) Reaction favors formation of more products. 
D) Reaction has a larger amount of products than reactants. 
E) Reaction is at equilibrium.

Question 12

At equilibrium in a 10.0 L vessel,there are 7.6 × 10-2 moles of SO2,8.6 × 10-2 moles of O2,and 8.2 × 10-2 moles of SO3.What is the equilibrium constant (Kc)for the reaction:
2SO2(g)+ O2(g)⇌ 2SO3(g)

Accepted Answer

A) 7.4 × 10-3 
B) 12.5 
C) 135 
D) 13.5 
A) 7.4 × 10-3 
B) 12.5 
C) 135 
D) 13.5

Question 13

Determine the value of Kc for the following reaction if the equilibrium concentrations are as follows: [PCl5]eq = 0.56 M,[PCl3]eq = 0.23 M,[Cl2]eq = 4.4 M.
PCl5(g)⇌ PCl3(g)+ Cl2(g)

Accepted Answer

A) 1.8 
B) 0.93 
C) 0.55 
D) 1.1 
E) 0.76 
A) 1.8 
B) 0.93 
C) 0.55 
D) 1.1 
E) 0.76

Question 14

Kc is 1.67 × 1020 at 25°C for the formation of iron(III)oxalate complex ion:
Fe3+(aq)+ 3 C2O42-(aq)⇌ [Fe(C2O4)3]3-(aq).
If 0.0200 M Fe3+ is initially mixed with 1.00 M oxalate ion,what is the concentration of Fe3+ ion at equilibrium?

Accepted Answer

A) 1.44 × 10-22 M 
B) 0.0100 M 
C) 8.35 × 1019 M 
D) 6.94 × 1021 M 
A) 1.44 × 10-22 M 
B) 0.0100 M 
C) 8.35 × 1019 M 
D) 6.94 × 1021 M

Question 15

Match the following.
-Q < K

Accepted Answer

A) Reaction will favor formation of reactants. 
B) Reaction does not strongly favor reactants or products. 
C) Reaction favors formation of more products. 
D) Reaction has a larger amount of products than reactants. 
E) Reaction is at equilibrium. 
A) Reaction will favor formation of reactants. 
B) Reaction does not strongly favor reactants or products. 
C) Reaction favors formation of more products. 
D) Reaction has a larger amount of products than reactants. 
E) Reaction is at equilibrium.

Question 16

Express the equilibrium constant for the following reaction.
H2(g)+ Br2(g)⇌ 2 HBr(g)

Accepted Answer

A) K =   
B) K =   
C) K =   
D) K =   
E) K =   
A) K =   
B) K =   
C) K =   
D) K =   
E) K =

Question 17

For which reaction will Kp = Kc?

Accepted Answer

A) S(s)+ O2(g)⇌ SO2(g) 
B) 2 HgO(s)⇌ Hg(l)+ O2(g) 
C) CaCO3(s)⇌ CaO(s)+ CO2(g) 
D) H2CO3(s)⇌ H2O(l)+ CO2(g) 
E) 2 H2O(l)⇌ 2 H2(g)+ O2(g) 
A) S(s)+ O2(g)⇌ SO2(g) 
B) 2 HgO(s)⇌ Hg(l)+ O2(g) 
C) CaCO3(s)⇌ CaO(s)+ CO2(g) 
D) H2CO3(s)⇌ H2O(l)+ CO2(g) 
E) 2 H2O(l)⇌ 2 H2(g)+ O2(g)

Question 18

Consider the following reaction at equilibrium.What effect will adding 1 atm of Ar to the reaction mixture have on the system?
2 H2S(g)+ 3 O2(g)⇌ 2 H2O(g)+ 2 SO2(g)

Accepted Answer

A) The reaction will shift to the right in the direction of products. 
B) No effect will be observed. 
C) The reaction will shift to the left in the direction of reactants. 
D) The equilibrium constant will decrease. 
E) The equilibrium constant will increase. 
A) The reaction will shift to the right in the direction of products. 
B) No effect will be observed. 
C) The reaction will shift to the left in the direction of reactants. 
D) The equilibrium constant will decrease. 
E) The equilibrium constant will increase.

Question 19

The equilibrium constant is given for one of the reactions below.Determine the value of the missing equilibrium constant.
H2(g)+ Br2(g)⇌ 2 HBr(g)Kc = 3.8 × 104
2 HBr(g)⇌ H2(g)+ Br2(g)Kc = ?

Accepted Answer

A) 1.9 × 104 
B) 5.3 × 10-5 
C) 2.6 × 10-5 
D) 6.4 × 10-4 
E) 1.6 × 103 
A) 1.9 × 104 
B) 5.3 × 10-5 
C) 2.6 × 10-5 
D) 6.4 × 10-4 
E) 1.6 × 103

Question 20

What will happen to the following exothermic reaction at equilibrium if the pressure is raised?
N2(g)+ 3H2(g)⇌ 2NH3(g)

Accepted Answer

A) Less NH3 will be produced. 
B) More N2 and H2 will be produced. 
C) There will be no change in concentrations. 
D) More NH3 will be produced. 
A) Less NH3 will be produced. 
B) More N2 and H2 will be produced. 
C) There will be no change in concentrations. 
D) More NH3 will be produced.

Why aren't solids or liquids included in an equilibrium expression?

Consider the following reaction,equilibrium concentrations,and equilibrium constant at a particular temperature.Determine the equilibrium concentration of SO₃(g). 2 SO₂(g)+ O₂(g)⇌ 2 SO₃(g)K_c = 1.7 × 10⁸ [SO₂]_eq = 0.0034 M [O₂]_eq = 0.0018 M

Consider the following reaction at equilibrium.What effect will adding water have on the system? CO₂(g)+ 2 H₂O(l)⇌ CH₄(g)+ 2 O₂(g)ΔH° = +890 kJ

The reaction below has a K_c value of 1.0 × 10¹².What is the value of K_p for this reaction at 500 K? 2 SO₂(g)+ O₂(g)⇌ 2 SO₃(g)

The equilibrium constant for the reaction A(g)LB(g)is 10².A reaction mixture initially contains [A] = 10.1 M and [B] = 0.0 M.Which statement is true at equilibrium?

For the reaction: N₂(g)+ 2 O₂(g)⇌ 2 NO₂(g),K_c = 8.3 × 10^-10 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?

Consider the following reaction,equilibrium concentrations,and equilibrium constant at a particular temperature.Determine the equilibrium concentration of H₂O(g). C₂H₄(g)+ H₂O(g)⇌ C₂H₅OH(g)K_c = 9.0 × 10³ [C₂H₄]_eq = 0.015 M [C₂H₅OH]_eq = 1.69 M

The equilibrium constant is given for one of the reactions below.Determine the value of the missing equilibrium constant. 2 SO₂(g)+ O₂(g)⇌ 2 SO₃(g)K_c = 1.7 × 10⁶ SO₃(g)⇌ 1/2 O₂(g)+ SO₂(g)K_c = ?

Match the following. -Q >> 1

Match the following. -K << 1

At equilibrium in a 10.0 L vessel,there are 7.6 × 10^-2 moles of SO₂,8.6 × 10^-2 moles of O₂,and 8.2 × 10^-2 moles of SO₃.What is the equilibrium constant (K_c)for the reaction: 2SO₂(g)+ O₂(g)⇌ 2SO₃(g)

Determine the value of K_c for the following reaction if the equilibrium concentrations are as follows: [PCl₅]_eq = 0.56 M,[PCl₃]_eq = 0.23 M,[Cl₂]_eq = 4.4 M. PCl₅(g)⇌ PCl₃(g)+ Cl₂(g)

K_c is 1.67 × 10²⁰ at 25°C for the formation of iron(III)oxalate complex ion: Fe³⁺(aq)+ 3 C₂O₄^2-(aq)⇌ [Fe(C₂O₄)₃]^3-(aq). If 0.0200 M Fe³⁺ is initially mixed with 1.00 M oxalate ion,what is the concentration of Fe³⁺ ion at equilibrium?

Match the following. -Q < K

Express the equilibrium constant for the following reaction. H₂(g)+ Br₂(g)⇌ 2 HBr(g)

For which reaction will K_p = K_c?

Consider the following reaction at equilibrium.What effect will adding 1 atm of Ar to the reaction mixture have on the system? 2 H₂S(g)+ 3 O₂(g)⇌ 2 H₂O(g)+ 2 SO₂(g)

The equilibrium constant is given for one of the reactions below.Determine the value of the missing equilibrium constant. H₂(g)+ Br₂(g)⇌ 2 HBr(g)K_c = 3.8 × 10⁴ 2 HBr(g)⇌ H₂(g)+ Br₂(g)K_c = ?

What will happen to the following exothermic reaction at equilibrium if the pressure is raised? N₂(g)+ 3H₂(g)⇌ 2NH₃(g)

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Exam 14: Chemical Equilibrium

Why aren't solids or liquids included in an equilibrium expression?

Consider the following reaction,equilibrium concentrations,and equilibrium constant at a particular temperature.Determine the equilibrium concentration of SO3(g). 2 SO2(g)+ O2(g)⇌ 2 SO3(g)Kc = 1.7 × 108 [SO2]eq = 0.0034 M [O2]eq = 0.0018 M

Consider the following reaction at equilibrium.What effect will adding water have on the system? CO2(g)+ 2 H2O(l)⇌ CH4(g)+ 2 O2(g)ΔH° = +890 kJ

The reaction below has a Kc value of 1.0 × 1012.What is the value of Kp for this reaction at 500 K? 2 SO2(g)+ O2(g)⇌ 2 SO3(g)

The equilibrium constant for the reaction A(g)LB(g)is 102.A reaction mixture initially contains [A] = 10.1 M and [B] = 0.0 M.Which statement is true at equilibrium?

For the reaction: N2(g)+ 2 O2(g)⇌ 2 NO2(g),Kc = 8.3 × 10-10 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?

Consider the following reaction,equilibrium concentrations,and equilibrium constant at a particular temperature.Determine the equilibrium concentration of H2O(g). C2H4(g)+ H2O(g)⇌ C2H5OH(g)Kc = 9.0 × 103 [C2H4]eq = 0.015 M [C2H5OH]eq = 1.69 M

The equilibrium constant is given for one of the reactions below.Determine the value of the missing equilibrium constant. 2 SO2(g)+ O2(g)⇌ 2 SO3(g)Kc = 1.7 × 106 SO3(g)⇌ 1/2 O2(g)+ SO2(g)Kc = ?

Match the following. -Q >> 1

Match the following. -K << 1

At equilibrium in a 10.0 L vessel,there are 7.6 × 10-2 moles of SO2,8.6 × 10-2 moles of O2,and 8.2 × 10-2 moles of SO3.What is the equilibrium constant (Kc)for the reaction: 2SO2(g)+ O2(g)⇌ 2SO3(g)

Determine the value of Kc for the following reaction if the equilibrium concentrations are as follows: [PCl5]eq = 0.56 M,[PCl3]eq = 0.23 M,[Cl2]eq = 4.4 M. PCl5(g)⇌ PCl3(g)+ Cl2(g)

Kc is 1.67 × 1020 at 25°C for the formation of iron(III)oxalate complex ion: Fe3+(aq)+ 3 C2O42-(aq)⇌ [Fe(C2O4)3]3-(aq). If 0.0200 M Fe3+ is initially mixed with 1.00 M oxalate ion,what is the concentration of Fe3+ ion at equilibrium?

Match the following. -Q < K

Express the equilibrium constant for the following reaction. H2(g)+ Br2(g)⇌ 2 HBr(g)

For which reaction will Kp = Kc?

Consider the following reaction at equilibrium.What effect will adding 1 atm of Ar to the reaction mixture have on the system? 2 H2S(g)+ 3 O2(g)⇌ 2 H2O(g)+ 2 SO2(g)

The equilibrium constant is given for one of the reactions below.Determine the value of the missing equilibrium constant. H2(g)+ Br2(g)⇌ 2 HBr(g)Kc = 3.8 × 104 2 HBr(g)⇌ H2(g)+ Br2(g)Kc = ?

What will happen to the following exothermic reaction at equilibrium if the pressure is raised? N2(g)+ 3H2(g)⇌ 2NH3(g)

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Thermochemistry

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Consider the following reaction,equilibrium concentrations,and equilibrium constant at a particular temperature.Determine the equilibrium concentration of SO₃(g). 2 SO₂(g)+ O₂(g)⇌ 2 SO₃(g)K_c = 1.7 × 10⁸ [SO₂]_eq = 0.0034 M [O₂]_eq = 0.0018 M

Consider the following reaction at equilibrium.What effect will adding water have on the system? CO₂(g)+ 2 H₂O(l)⇌ CH₄(g)+ 2 O₂(g)ΔH° = +890 kJ

The reaction below has a K_c value of 1.0 × 10¹².What is the value of K_p for this reaction at 500 K? 2 SO₂(g)+ O₂(g)⇌ 2 SO₃(g)

The equilibrium constant for the reaction A(g)LB(g)is 10².A reaction mixture initially contains [A] = 10.1 M and [B] = 0.0 M.Which statement is true at equilibrium?

For the reaction: N₂(g)+ 2 O₂(g)⇌ 2 NO₂(g),K_c = 8.3 × 10^-10 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?

Consider the following reaction,equilibrium concentrations,and equilibrium constant at a particular temperature.Determine the equilibrium concentration of H₂O(g). C₂H₄(g)+ H₂O(g)⇌ C₂H₅OH(g)K_c = 9.0 × 10³ [C₂H₄]_eq = 0.015 M [C₂H₅OH]_eq = 1.69 M

The equilibrium constant is given for one of the reactions below.Determine the value of the missing equilibrium constant. 2 SO₂(g)+ O₂(g)⇌ 2 SO₃(g)K_c = 1.7 × 10⁶ SO₃(g)⇌ 1/2 O₂(g)+ SO₂(g)K_c = ?

At equilibrium in a 10.0 L vessel,there are 7.6 × 10^-2 moles of SO₂,8.6 × 10^-2 moles of O₂,and 8.2 × 10^-2 moles of SO₃.What is the equilibrium constant (K_c)for the reaction: 2SO₂(g)+ O₂(g)⇌ 2SO₃(g)

Determine the value of K_c for the following reaction if the equilibrium concentrations are as follows: [PCl₅]_eq = 0.56 M,[PCl₃]_eq = 0.23 M,[Cl₂]_eq = 4.4 M. PCl₅(g)⇌ PCl₃(g)+ Cl₂(g)

K_c is 1.67 × 10²⁰ at 25°C for the formation of iron(III)oxalate complex ion: Fe³⁺(aq)+ 3 C₂O₄^2-(aq)⇌ [Fe(C₂O₄)₃]^3-(aq). If 0.0200 M Fe³⁺ is initially mixed with 1.00 M oxalate ion,what is the concentration of Fe³⁺ ion at equilibrium?

Express the equilibrium constant for the following reaction. H₂(g)+ Br₂(g)⇌ 2 HBr(g)

For which reaction will K_p = K_c?

Consider the following reaction at equilibrium.What effect will adding 1 atm of Ar to the reaction mixture have on the system? 2 H₂S(g)+ 3 O₂(g)⇌ 2 H₂O(g)+ 2 SO₂(g)

The equilibrium constant is given for one of the reactions below.Determine the value of the missing equilibrium constant. H₂(g)+ Br₂(g)⇌ 2 HBr(g)K_c = 3.8 × 10⁴ 2 HBr(g)⇌ H₂(g)+ Br₂(g)K_c = ?

What will happen to the following exothermic reaction at equilibrium if the pressure is raised? N₂(g)+ 3H₂(g)⇌ 2NH₃(g)