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9.4 Naming and Writing 9.4 Naming and Writing Formulas for Acids and BasesFormulas for Acids and Bases
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Chapter 9Chemical Names and Formulas
9.1 Naming Ions9.2 Naming and Writing Formulas for Ionic
Compounds9.3 Naming and Writing Formulas for Molecular
Compounds
9.4 Naming and Writing Formulas forAcids and Bases
9.5 The Laws Governing How Compounds Form
9.4 Naming and Writing 9.4 Naming and Writing Formulas for Acids and BasesFormulas for Acids and Bases
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What’s the name of the acid responsible for the crisp taste in this drink?
There’s a certain acid that gives many soft drinks their crisp, enjoyable taste.
CHEMISTRY & YOUCHEMISTRY & YOU
9.4 Naming and Writing 9.4 Naming and Writing Formulas for Acids and BasesFormulas for Acids and Bases
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Names and Formulas of Acids
How do you determine the name and formula of an acid?
Names andNames andFormulas of AcidsFormulas of Acids
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• Acids are a group of ionic compounds with unique properties.
• Acids can be defined in several ways.• For now, it is enough to know that an
acid is a compound that contains one or more hydrogen atoms and produces hydrogen ions when dissolved in water.
Names and Names and Formulas of AcidsFormulas of Acids
9.4 Naming and Writing 9.4 Naming and Writing Formulas for Acids and BasesFormulas for Acids and Bases
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• Acids have many uses.
• For example, sulfuric acid is often used to etch circuit boards like the one shown below.
Names and Names and Formulas of AcidsFormulas of Acids
9.4 Naming and Writing 9.4 Naming and Writing Formulas for Acids and BasesFormulas for Acids and Bases
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• Three rules can help you name an acid with the general formula HnX dissolved in water.
1. When the name of the anion ends in -ide, the acid name begins with the prefix hydro-. The stem of the anion has the suffix -ic and is followed by the word acid.
• Therefore, HCl (X= chloride) is named hydrochloric acid.
Names and Names and Formulas of AcidsFormulas of Acids
9.4 Naming and Writing 9.4 Naming and Writing Formulas for Acids and BasesFormulas for Acids and Bases
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• Three rules can help you name an acid with the general formula HnX dissolved in water.
2. When the anion name ends in -ite, the acid name is the stem of the anion with the suffix -ous, followed by the word acid.
• Thus, H2SO3 (X = sulfite) is named sulfurous acid.
Names and Names and Formulas of AcidsFormulas of Acids
9.4 Naming and Writing 9.4 Naming and Writing Formulas for Acids and BasesFormulas for Acids and Bases
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• Three rules can help you name an acid with the general formula HnX dissolved in water.
3. When the anion name ends in -ate, the acid name is the stem of the anion with the suffix -ic, followed by the word acid.
• Thus, HNO3 (X = nitrate) is named nitric acid.
Names and Names and Formulas of AcidsFormulas of Acids
9.4 Naming and Writing 9.4 Naming and Writing Formulas for Acids and BasesFormulas for Acids and Bases
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Names and Names and Formulas of AcidsFormulas of Acids
These three rules for naming an acid with the general formula HnX dissolved in water are summarized in the table below.
Naming Common Acids
Anion ending
Example Acid name Example
-ide chloride, Cl– hydro-(stem)-ic acid hydrochloric acid
-ite sulfite, SO3– (stem)-ous acid sulfurous acid
-ate nitrate, NO3– (stem)-ic acid nitric acid
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An acid that provides the crisp taste in many soft drinks has the formula H3PO4. What’s the name of this acid?
CHEMISTRY & YOUCHEMISTRY & YOU
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An acid that provides the crisp taste in many soft drinks has the formula H3PO4. What’s the name of this acid?
The name of this acid is phosphoric acid.
CHEMISTRY & YOUCHEMISTRY & YOU
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To write the formula for an acid, use the rule for writing the name of the acid in reverse. Then, balance the ionic charges just as you would for any ionic compound.
Names and Names and Formulas of AcidsFormulas of Acids
Writing Formulas of Acids
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Names and Names and Formulas of AcidsFormulas of Acids
• Many industrial processes, including steel and fertilizer manufacturing, use acids.
• You should become familiar with the names and formulas of common acids such as those listed in the table at right.
Writing Formulas of Acids
Common Acids
Name Formula
Hydrochloric acid HCl
Sulfuric acid H2SO4
Nitric acid HNO3
Ethanoic acid HC2H3O2
Phosphoric acid H3PO4
Carbonic acid H2CO3
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Sample Problem 9.8Sample Problem 9.8
Naming Acids
Name the following compounds as acids.
a. HClO
b. HCN
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Sample Problem 9.8Sample Problem 9.8
Analyze Identify the relevant concepts.
The anion of the acid determines the acid name. (1) If the name of the anion ends in -ide, name the acid using the stem of the anion with the prefix hydro- and the suffix -ic, followed by the word acid. (2) If the anion name ends in -ite, name the acid using the stem of the anion with the suffix -ous, followed by the word acid. (3) If the anion name ends in -ate, name the acid using the stem of the anion with the suffix -ic, followed by the word acid.
1
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Sample Problem 9.8Sample Problem 9.8
Solve Apply concepts to this problem.
Identify the anion in the acid and the suffix of the anion name.
a. HClO: ClO–, (hypochlorite)
b. HCN: CN–, (cyanide)
2
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Sample Problem 9.8Sample Problem 9.8
Solve Apply concepts to this problem.
Name the acid using the appropriate prefix (if any) and suffix. Finish with the word acid.
a. HClO: ClO–, (hypochlorite)
hypochlorous acid (Rule 2)
b. HCN: CN–, (cyanide)
hydrocyanic acid (Rule 1)
2
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What is the name of the acid H2S?
(Hint: X = sulfide)
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What is the name of the acid H2S?
(Hint: X = sulfide)
H2S is named hydrosulfuric acid.
Use Rule 1: When the name of the anion ends in -ide, the acid name begins with the prefix hydro-. The stem of the anion has the suffix -ic and is followed by the word acid.
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Names and Formulas of Bases
How do you determine the name and formula of a base?
Names and Formulas Names and Formulas of Basesof Bases
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• A base is generally an ionic compound that produces hydroxide ions when dissolved in water.
Bases are named in the same way as other ionic compounds—the name of the cation is followed by the name of the anion.
Names and Formulas Names and Formulas of Basesof Bases
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• The common base sodium hydroxide is used in making cleaners, soap, and paper, as shown in the figure at right.
• Sodium hydroxide (NaOH) is composed of sodium cations (Na+) and hydroxide anions (OH–).
Names and Formulas Names and Formulas of Basesof Bases
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To write the formula for a base, first write the symbol for the metal cation followed by the formula for the hydroxide ion. Then, balance the ionic charges just as you would for any ionic compound.
Names and Formulas Names and Formulas of Basesof Bases
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Is the naming of a base more similar to the naming of an acid or to the naming of other ionic compounds?
Unlike acids, bases are named in the same way as other ionic compounds.
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• acid: a compound that produces hydrogen ions in solution; see also hydrogen-ion donor, Lewis acid
• base: a compound that produces hydroxide ions in solution; see also hydrogen-ion acceptor, Lewis base
Glossary TermsGlossary Terms
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END OF 9.4END OF 9.4