Question

Name these acids: (a) \(\mathrm{HNO}_{2}\) (d) \(\mathrm{HBr}\) (g) \(\mathrm{HF}\) (b) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (e) \(\mathrm{H}_{3} \mathrm{PO}_{3}\) (h) \(\mathrm{HBrO}_{3}\) (c) \(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\) (f) \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\) (i) \(\mathrm{HIO}_{4}\)

Short answer

(a) Nitrous acid, (d) Hydrobromic acid, (g) Hydrofluoric acid, (b) Sulfuric acid, (e) Phosphorous acid, (h) Bromic acid, (c) Oxalic acid, (f) Acetic acid, (i) Periodic acid.

Step-by-step solution

Naming Monatomic Acids

For monatomic acids, which are acids with hydrogen and one other nonmetal, the prefix 'hydro-' is added to the root of the nonmetal's name followed by the suffix '-ic' and the word 'acid'. For example, (a) \(\mathrm{HBr}\) is named hydrobromic acid, (g) \(\mathrm{HF}\) is named hydrofluoric acid.

Naming Oxyacids

Oxyacids contain hydrogen, oxygen, and another element. If the polyatomic ion ends in '-ate', the acid name is the stem of the polyatomic ion with '-ic' followed by 'acid'. If the ion ends in '-ite', the acid name is the stem plus '-ous' followed by 'acid'. For example, (a) \(\mathrm{HNO}_{2}\) is named nitrous acid because the polyatomic ion \(\mathrm{NO}_{2}^{-}\) is nitrite, (h) \(\mathrm{HBrO}_{3}\) is named bromic acid because the polyatomic ion \(\mathrm{BrO}_{3}^{-}\) is bromate, (i) \(\mathrm{HIO}_{4}\) is named periodic acid because the polyatomic ion \(\mathrm{IO}_{4}^{-}\) is periodate.

Naming Acids with Polyatomic Ions

For acids based on polyatomic ions and having a prefix in the name of the original ion, the same prefix is retained in the acid name. For example, (b) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) is named sulfuric acid, (e) \(\mathrm{H}_{3} \mathrm{PO}_{3}\) is named phosphorous acid, (c) \(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\) is named oxalic acid because the corresponding polyatomic ion is oxalate.

Naming Carboxylic Acids

Some acids, like carboxylic acids, have their own common names. For example, (f) \(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\) is commonly known as acetic acid.

Key concepts

Monatomic Acids

Monatomic acids are the simplest type of acids, consisting of hydrogen and only one other nonmetal element. When naming them, the protocol begins with the prefix 'hydro-', then the root of the nonmetal's name, and concludes with the suffix '-ic', followed by the word 'acid'. For example, hydrogen bromide (HBr) becomes hydrobromic acid, and hydrogen fluoride (HF) is named hydrofluoric acid. These names clearly indicate that the substances are acidic and contain a single additional element besides hydrogen.

Understanding the structure of monatomic acids is crucial for students, as it lays the foundation for recognizing how acid names are derived from their chemical formulas. This connection between naming and chemical structure is essential for mastering chemical nomenclature.

Oxyacids

Oxyacids are more complex than monatomic acids, as they contain hydrogen, oxygen, and another element. The name of an oxyacid is determined by the polyatomic ion it contains. If the polyatomic ion ends with '-ate', the acid is named with the stem of that ion plus '-ic acid'. Conversely, if the ion ends with '-ite', the acid's name will have the stem plus '-ous acid'.

For instance, nitrous acid is so named because the corresponding polyatomic ion is nitrite (o{NO2^-}), while bromic acid comes from the bromate ion (o{BrO3^-}). Students should familiarize themselves with common polyatomic ions to name oxyacids correctly. Knowing these ion names can also aid in understanding patterns and predicting the names of other acids.

Polyatomic Ions

Polyatomic ions are charged particles that consist of two or more atoms covalently bonded together. These ions play a key role in the naming of acids and salts. When an acid is derived from a polyatomic ion, the name of the acid reflects the name of the ion.

For example, sulfuric acid (o{H2SO4}) corresponds to the sulfate ion (o{SO4^2-}), and phosphorous acid (o{H3PO3}) is related to the phosphite ion. Polyatomic ions with specific prefixes like 'hypo-' or 'per-' retain these prefixes in their acid names, which hints at their relative oxygen content. Students are encouraged to learn the most common polyatomic ions, as these will repeatedly appear in various chemical compounds, extending beyond acids.

Carboxylic Acids

Carboxylic acids are organic compounds containing a functional group with the formula o{-COOH}. They are characterized by a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (-OH). Unlike inorganic acids, carboxylic acids often have common names, such as acetic acid (o{HC2H3O2}), which is the acid found in vinegar.

These acids are widespread in nature and industry, and their names are not always systematic. For example, formic acid (from the ant, or 'formica' in Latin) and acetic acid are historical names that persist in modern usage. When studying carboxylic acids, students should remember both their common and systematic names for a comprehensive understanding of organic chemistry.