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Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
89
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 9
Reactions that form water or a gas Some double-replacement
reactions in aqueous solution produce water or a gas (or both) rather
than a precipitate. In such cases, the water or gas is shown as a product in the net ionic equation, as are the ions that produced it. The
remaining ions are eliminated as spectator ions. The following
example problem illustrates this concept.
Example Problem 9-5
Writing Equations for a Reaction That Produces Water
When hydrochloric acid and potassium hydroxide solutions are
mixed, water results, together with an aqueous solution of potassium
chloride. Write the balanced chemical equation, a complete ionic
equation, and a net ionic equation for this reaction.
The balanced chemical equation is the same as the skeleton equation.
HCl(aq) ϩ KOH(aq) 0 H 2 O(l) ϩ KCl(aq)
Write the complete ionic equation, which includes all of the ions.
H ϩ (aq) ϩ Cl Ϫ (aq) ϩ K ϩ (aq) ϩ OH Ϫ (aq) 0
H 2 O(l) ϩ K ϩ (aq) ϩ Cl Ϫ (aq)
Remove the spectator ions to produce the net ionic equation.
H ϩ (aq) ϩ OH Ϫ (aq) 0 H 2 O(l)
Practice Problems
7. Write balanced chemical, complete ionic, and net ionic equations for the reactions between the following substances, which
produce water.
a. nitric acid (HNO 3 ) and aqueous barium hydroxide
b. sulfuric acid (H 2 SO 4 ) and aqueous sodium hydroxide
c. phosphoric acid (H 3 PO 4 ) and aqueous lithium hydroxide
Example Problem 9-6
Writing Equations for a Reaction That Produces a Gas
Write balanced chemical, complete ionic, and net ionic equations for
the reaction between aqueous solutions of sodium sulfide and
hydrochloric acid. Hydrogen sulfide gas is produced, along with an
aqueous solution of sodium chloride.
▲
Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
89
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 9
Reactions that form water or a gas Some double-replacement
reactions in aqueous solution produce water or a gas (or both) rather
than a precipitate. In such cases, the water or gas is shown as a product in the net ionic equation, as are the ions that produced it. The
remaining ions are eliminated as spectator ions. The following
example problem illustrates this concept.
Example Problem 9-5
Writing Equations for a Reaction That Produces Water
When hydrochloric acid and potassium hydroxide solutions are
mixed, water results, together with an aqueous solution of potassium
chloride. Write the balanced chemical equation, a complete ionic
equation, and a net ionic equation for this reaction.
The balanced chemical equation is the same as the skeleton equation.
HCl(aq) ϩ KOH(aq) 0 H 2 O(l) ϩ KCl(aq)
Write the complete ionic equation, which includes all of the ions.
H ϩ (aq) ϩ Cl Ϫ (aq) ϩ K ϩ (aq) ϩ OH Ϫ (aq) 0
H 2 O(l) ϩ K ϩ (aq) ϩ Cl Ϫ (aq)
Remove the spectator ions to produce the net ionic equation.
H ϩ (aq) ϩ OH Ϫ (aq) 0 H 2 O(l)
Practice Problems
7. Write balanced chemical, complete ionic, and net ionic equations for the reactions between the following substances, which
produce water.
a. nitric acid (HNO 3 ) and aqueous barium hydroxide
b. sulfuric acid (H 2 SO 4 ) and aqueous sodium hydroxide
c. phosphoric acid (H 3 PO 4 ) and aqueous lithium hydroxide
Example Problem 9-6
Writing Equations for a Reaction That Produces a Gas
Write balanced chemical, complete ionic, and net ionic equations for
the reaction between aqueous solutions of sodium sulfide and
hydrochloric acid. Hydrogen sulfide gas is produced, along with an
aqueous solution of sodium chloride.
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