9.4 naming and writing formulas for acids and bases 1 > copyright © pearson education, inc., or...

9.4 Naming and Writing 9.4 Naming and Writing Formulas for Acids and BasesFormulas for Acids and Bases

1

>>

Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

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


2

>>


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


3

>>


Names and Formulas of Acids

How do you determine the name and formula of an acid?

Names andNames andFormulas of AcidsFormulas of Acids


4

>>


• 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


5

>>


• Acids have many uses.

• For example, sulfuric acid is often used to etch circuit boards like the one shown below.



6

>>


• 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.



7

>>



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.



8

>>



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.



9

>>



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


10

>>


An acid that provides the crisp taste in many soft drinks has the formula H3PO4. What’s the name of this acid?



11

>>


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.



12

>>


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.


Writing Formulas of Acids


13

>>



• 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


14

>>


Sample Problem 9.8Sample Problem 9.8

Naming Acids

Name the following compounds as acids.

a. HClO

b. HCN


15

>>



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


16

>>



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


17

>>



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


18

>>


What is the name of the acid H2S?

(Hint: X = sulfide)


19

>>


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.


20

>>


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


21

>>


• 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.



22

>>


• 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–).



23

>>


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.



24

>>


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.


25

>>


• 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


26

>>


END OF 9.4END OF 9.4

9.4 naming and writing formulas for acids and bases 1 > copyright © pearson education, inc., or...

Documents

formulas of acids

writing formulas

word acid

certain acid

acid responsible

hydrochloric acid

nitric acid

sulfurous acid