Write The Formulas For Acids

vii.3: Names and Formulas of Acids

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Acids

An acid tin exist defined in several ways. The almost straightforward definition is that an acrid is a molecular compound that contains one or more hydrogen atoms and produces hydrogen ions \(\left( \ce{H^+} \right)\) when dissolved in water.

Effigy \(\PageIndex{1}\): (A) Vinegar comes in a diversity of types, simply all contain acetic acid. (B) Citrus fruits like grapefruit contain citric and ascorbic acids.

This is a different type of chemical compound than the others we have seen and so far. Acids are molecular, which means that in their pure state they are individual molecules and practise not prefer the extended three-dimensional structures of ionic compounds like \(\ce{NaCl}\). However, when these molecules are dissolved in water, the chemical bond between the hydrogen cantlet and the rest of the molecule breaks, leaving a positively-charged hydrogen ion and an anion. This can be symbolized in a chemical equation:

\[\ce{HCl} \rightarrow \ce{H^+} + \ce{Cl^-}\]

Since acids produce \(\ce{H^+}\) cations upon dissolving in water, the \(\ce{H}\) of an acid is written get-go in the formula of an inorganic acid. The balance of the acid (other than the \(\ce{H}\)) is the anion afterward the acid dissolves. Organic acids are besides an of import class of compounds, only will non be discussed here.

Naming Acids

Since all acids contain hydrogen, the proper name of an acid is based on the anion that goes with it. These anions tin can either exist monatomic or polyatomic.

Naming Binary acids (in aqueous form)

A binary acid is an acrid that consists of hydrogen and one other element. The most common binary acids contain a halogen. The acid name begins with the prefix hydro- . followed by the base of operations name of the anion, followed past the suffix -ic .

Formula for naming acids: Hydro- and Base name of nonmetal and -ic + acid. Example: HCl is hydrochloric acid.

Naming Oxyacids

An oxyacid is an acid that consists of hydrogen, oxygen, and a 3rd chemical element. The third element is usually a nonmetal.

a. Oxyanions with -ite ending.

The name of the acid is the root of the anion followed past the suffix -ous . There is no prefix.

Formula for naming oxyanions with -ite ending: Base name of oxyanion and -ous + acid. Example: H2SO3 is sulfurous acid.

b. Oxyanions with -ate ending.

The name of the acrid is the root of the anion followed by the suffix -ic . There is no prefix.

Formula for naming oxyanions with -ate ending: Base name of oxyanion and -ic + acid. Example: H3PO4 is phosphoric acid.

Note

The base of operations proper name for sulfur containing oxyacid is sulfur- instead of simply sulf- . The same is true for a phosphorus containing oxyacid. The base name is phosphor- instead of simply phosph- .

Writing Formulas for Acids

Like other compounds that we have studied, acids are electrically neutral. Therefore, the charge of the anion part of the formula must exist exactly balanced out by the \(\ce{H^+}\) ions. Another way to call back about writing the correct formula is to use the crisscross method, shown below for sulfuric acid.

H2SO4: H has +1 charge and SO4 has -2 charge, so there must be 2 H+ and 1 SO4 for the charges to balance out.

Formula: H_twoSO₄

Effigy \(\PageIndex{ii}\): Crisscross arroyo to writing formula for sulfuric acid.

Summary

Acids are molecular compounds that release hydrogen ions.
A binary acid consists of hydrogen and 1 other element.
Oxyacids contain hydrogen, oxygen, and one other element.
The name of the acrid is based on the anion fastened to the hydrogen.

Contributions & Attributions

This page was synthetic from content via the post-obit contributor(s) and edited (topically or extensively) by the LibreTexts development team to meet platform manner, presentation, and quality:

Marisa Alviar-Agnew (Sacramento City College)
Henry Agnew (UC Davis)