Unit 4 Chemical Systems and Equilibrium
Solutions to Chapter 7 Chemical Equilibrium Practice Problems
Equilibrium Constant Expressions for Homogeneous Chemical Systems
(Student textbook page 428)
1. Write the equilibrium constant expression for the reaction at 200°C between ethanol and
ethanoic acid to form ethyl ethanoate and water:
CH3CH2OH(g) + CH3COOH(g) ⇌ CH3COOCH2CH3(g) + H2O(g)
What Is Required?
You need to write the expression for the equilibrium constant, Keq.
What Is Given?
You know the balanced chemical equation.
Plan Your Strategy Act on Your Strategy
The expression for the equilibrium constant
follows the form:
K eq
CH3 COOCH2 CH3 H2 O
[C]c [D]d
Keq = where [A], [B], [C], and [D] CH3CH2 OHCH3COOH
[A]a [B]b
represent the concentrations of the reactants
and products at equilibrium. The exponents a,
b, c, and d are the stoichiometric coefficients
from the balanced chemical equation. Follow
this format using the reactants, products, and
coefficients in the given equation.
Check Your Solution
The square brackets indicate the concentration in mol/L. The products are in the numerator
and the reactants are in the denominator and each is raised to the power of 1 which is each
coefficient in the balanced equation.
Unit 4 Part B ● MHR 1
,2. Write the equilibrium constant expression for the reaction between nitrogen gas and oxygen
gas at high temperatures is given by the following balanced chemical reaction:
N2(g) + O2(g) ⇌ 2NO(g)
What Is Required?
You need to write the expression for the equilibrium constant, Keq.
What Is Given?
You know the balanced chemical equation.
Plan Your Strategy Act on Your Strategy
The expression for the equilibrium constant NO
2
follows the form: Keq =
[C]c [D]d
N 2 O2
Keq = where [A], [B], [C], and [D]
[A]a [B]b
represent the concentrations of the reactants
and products at equilibrium. The exponents a,
b, c, and d are the stoichiometric coefficients
from the balanced chemical equation. Follow
this format using the reactants, products, and
coefficients in the given equation.
Check Your Solution
The square brackets indicate the concentration in mol/L. The product is in the numerator, the
reactants are in the denominator and each is raised to power of its coefficient in the balanced
chemical equation.
2 MHR ● Chemistry 12 Solutions Manual 978-0-07-106042-4
,3. Write the equilibrium constant expression for the reaction between hydrogen gas and oxygen
gas to form water vapour:
2H2(g) + O2(g) ⇌ 2H2O(g)
What Is Required?
You need to write the expression for the equilibrium constant, Keq.
What Is Given?
You know the balanced chemical equation.
Plan Your Strategy Act on Your Strategy
The expression for the equilibrium constant H 2O
2
follows the form: Keq =
H 2 O2
2
[C]c [D]d
Keq = where [A], [B], [C], and [D]
[A]a [B]b
represent the concentrations of the reactants
and products at equilibrium. The exponents a,
b, c, and d are the stoichiometric coefficients
from the balanced chemical equation. Follow
this format using the reactants, products, and
coefficients in the given equation.
Check Your Solution
The square brackets indicate the concentration in mol/L. The product is in the numerator and
the reactants are in the denominator and each is raised to power of its coefficient in the
balanced chemical equation.
Unit 4 Part B ● MHR 3
, 4. Write the equilibrium constant expression for the oxidation of ammonia (one of the reactions
in the manufacture of nitric acid):
4NH3(g) + 5O2(g) ⇌ 4NO(g) + 6H2O(g)
What Is Required?
You need to write the expression for the equilibrium constant, Keq.
What Is Given?
You know the balanced equation.
Plan Your Strategy Act on Your Strategy
The expression for the equilibrium constant NO H 2 O
4 6
follows the form: Keq =
NH3 O2
4 5
[C]c [D]d
Keq = where [A], [B], [C], and [D]
[A]a [B]b
represent the concentrations of the reactants
and products at equilibrium. The exponents a,
b, c, and d are the stoichiometric coefficients
from the balanced equation. Follow this format
using the reactants, products, and coefficients
in the given equation.
Check Your Solution
The square brackets indicate the concentration in mol/L. The products are in the numerator,
the reactants are in the denominator, and each is raised to power of its coefficient in the
balanced chemical equation.
4 MHR ● Chemistry 12 Solutions Manual 978-0-07-106042-4
Solutions to Chapter 7 Chemical Equilibrium Practice Problems
Equilibrium Constant Expressions for Homogeneous Chemical Systems
(Student textbook page 428)
1. Write the equilibrium constant expression for the reaction at 200°C between ethanol and
ethanoic acid to form ethyl ethanoate and water:
CH3CH2OH(g) + CH3COOH(g) ⇌ CH3COOCH2CH3(g) + H2O(g)
What Is Required?
You need to write the expression for the equilibrium constant, Keq.
What Is Given?
You know the balanced chemical equation.
Plan Your Strategy Act on Your Strategy
The expression for the equilibrium constant
follows the form:
K eq
CH3 COOCH2 CH3 H2 O
[C]c [D]d
Keq = where [A], [B], [C], and [D] CH3CH2 OHCH3COOH
[A]a [B]b
represent the concentrations of the reactants
and products at equilibrium. The exponents a,
b, c, and d are the stoichiometric coefficients
from the balanced chemical equation. Follow
this format using the reactants, products, and
coefficients in the given equation.
Check Your Solution
The square brackets indicate the concentration in mol/L. The products are in the numerator
and the reactants are in the denominator and each is raised to the power of 1 which is each
coefficient in the balanced equation.
Unit 4 Part B ● MHR 1
,2. Write the equilibrium constant expression for the reaction between nitrogen gas and oxygen
gas at high temperatures is given by the following balanced chemical reaction:
N2(g) + O2(g) ⇌ 2NO(g)
What Is Required?
You need to write the expression for the equilibrium constant, Keq.
What Is Given?
You know the balanced chemical equation.
Plan Your Strategy Act on Your Strategy
The expression for the equilibrium constant NO
2
follows the form: Keq =
[C]c [D]d
N 2 O2
Keq = where [A], [B], [C], and [D]
[A]a [B]b
represent the concentrations of the reactants
and products at equilibrium. The exponents a,
b, c, and d are the stoichiometric coefficients
from the balanced chemical equation. Follow
this format using the reactants, products, and
coefficients in the given equation.
Check Your Solution
The square brackets indicate the concentration in mol/L. The product is in the numerator, the
reactants are in the denominator and each is raised to power of its coefficient in the balanced
chemical equation.
2 MHR ● Chemistry 12 Solutions Manual 978-0-07-106042-4
,3. Write the equilibrium constant expression for the reaction between hydrogen gas and oxygen
gas to form water vapour:
2H2(g) + O2(g) ⇌ 2H2O(g)
What Is Required?
You need to write the expression for the equilibrium constant, Keq.
What Is Given?
You know the balanced chemical equation.
Plan Your Strategy Act on Your Strategy
The expression for the equilibrium constant H 2O
2
follows the form: Keq =
H 2 O2
2
[C]c [D]d
Keq = where [A], [B], [C], and [D]
[A]a [B]b
represent the concentrations of the reactants
and products at equilibrium. The exponents a,
b, c, and d are the stoichiometric coefficients
from the balanced chemical equation. Follow
this format using the reactants, products, and
coefficients in the given equation.
Check Your Solution
The square brackets indicate the concentration in mol/L. The product is in the numerator and
the reactants are in the denominator and each is raised to power of its coefficient in the
balanced chemical equation.
Unit 4 Part B ● MHR 3
, 4. Write the equilibrium constant expression for the oxidation of ammonia (one of the reactions
in the manufacture of nitric acid):
4NH3(g) + 5O2(g) ⇌ 4NO(g) + 6H2O(g)
What Is Required?
You need to write the expression for the equilibrium constant, Keq.
What Is Given?
You know the balanced equation.
Plan Your Strategy Act on Your Strategy
The expression for the equilibrium constant NO H 2 O
4 6
follows the form: Keq =
NH3 O2
4 5
[C]c [D]d
Keq = where [A], [B], [C], and [D]
[A]a [B]b
represent the concentrations of the reactants
and products at equilibrium. The exponents a,
b, c, and d are the stoichiometric coefficients
from the balanced equation. Follow this format
using the reactants, products, and coefficients
in the given equation.
Check Your Solution
The square brackets indicate the concentration in mol/L. The products are in the numerator,
the reactants are in the denominator, and each is raised to power of its coefficient in the
balanced chemical equation.
4 MHR ● Chemistry 12 Solutions Manual 978-0-07-106042-4
