Introductory Chemistry: A Foundation - Zumdahl S.S., DeCoste D.J. 2019

Nomenclature
Naming Acids

Objectives

· To learn how the anion composition determines the acid’s name.

· To learn names for common acids.

When dissolved in water, certain molecules produce ions (protons). These substances, which are called acids , were first recognized by the sour taste of their solutions. For example, citric acid is responsible for the tartness of lemons and limes. Acids will be discussed in detail later. Here we simply present the rules for naming acids.

An acid can be viewed as a molecule with one or more ions attached to an anion. The rules for naming acids depend on whether the anion contains oxygen.

Rules for Naming Acids

1. If the anion does not contain oxygen, the acid is named with the prefix hydro- and the suffix -ic attached to the root name for the element. For example, when gaseous (hydrogen chloride) is dissolved in water, it forms hydrochloric acid. Similarly, hydrogen cyanide and dihydrogen sulfide dissolved in water are called hydrocyanic acid and hydrosulfuric acid, respectively.

2. When the anion contains oxygen, the acid name is formed from the root name of the central element of the anion or the anion name, with a suffix of -ic or -ous. When the anion name ends in -ate, the suffix -ic is used. For example,

3. When the anion name ends in -ite, the suffix -ous is used in the acid name. For example,

The application of Rule 2 can be seen in the following names of the acids of the oxyanions of chlorine:

The rules for naming acids are given in schematic form in Fig. 5.3. The names of the most important acids are given in Tables 5.5 and 5.6. These should be memorized.

Figure 5.3.

A flowchart for naming acids. An acid is best considered as one or more ions attached to an anion.

Table 5.5. Names of Acids That Do Not Contain Oxygen

Table 5.6. Names of Some Oxygen-Containing Acids