CHEMISTRY:Naming and Writing Formulas For Acids and Bases

*NOTE*

*Do not confuse phosphorous with phosphorus, the element name.*

What are the three rules for naming acids?

1. *When the name of the anion (X) 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(aq) (X = chloride) is named hydrochloric acid. H2S(aq) (X = sulfide) is named hydrosulfuric acid. 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 (aq) (X = sulfite) is named sulfurous acid. 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(aq) (X = nitrate) is named nitric acid.

How are bases named?

Bases are named in the same way as other ionic compounds—the name of the cation is followed by the name of the anion.

Each of the rules deals with an anion with a different suffix: -ide, -ite, and -ic.

Each of the rules deals with an anion with a different suffix: -ide, -ite, and -ic.

In some bases, the cation is not a metal ion but a polyatomic ion.

For example, in ammonium hydroxide (NH4OH), the cation is NH4+.

Common Acids

Name *:* Formula Hydrochloric acid *:* HCl Sulfuric acid *:* H2SO4 Nitric acid *:* HNO3 Acetic acid *:* CH3COOH Phosphoric acid *:* H3PO4 Carbonic acid *:* H2CO3

How are the formulas of acids determined?

Use the rules for writing the names of acids in reverse to write the formulas for acids.

Acids

a compound that contains one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water.

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

EXAMPLE

aluminum hydroxide consists of the aluminum cation (Al3+) and the hydroxide anion (OH−). You need three hydroxide ions to balance the 3+ charge of the aluminum cation. Thus the formula for aluminum hydroxide is Al(OH)3.

To write the formulas for bases...

write the symbol for the metal cation followed by the formula for the hydroxide ion. Balance the ionic charges just as you do for any ionic compound.

When naming an acid...

you can consider the acid to consist of an anion combined with as many hydrogen ions as are needed to make the molecule electrically neutral. the chemical formulas of acids are in the general form HnX where X is a monatomic or polyatomic anion and n is a subscript indicating the number of hydrogen ions that are combined with the anion.