Question

Give the name and formula for the acid derived from each of the following anions: (a) perchlorate (b) \(\mathrm{NO}_{3}^{-}\) (c) bromite (d) \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)

Short answer

(a) Perchloric acid \(\text{HClO}_4\), (b) Nitric acid \(\text{HNO}_3\), (c) Bromous acid \(\text{HBrO}_2\), (d) Phosphoric acid \(\text{H}_3\text{PO}_4\)

Step-by-step solution

Identify the anion and the acid naming pattern

Each anion corresponds to a particular acid following specific naming rules. Generally, for anions ending in '-ate', the suffix for the acid is '-ic'; for '-ite', the suffix is '-ous'. For individual rules regarding polyatomic ions with hydrogen, determine based on the hydrogen present.

Derive the acid name and formula from perchlorate

Perchlorate is \(\text{ClO}_4^-\). Adding hydrogen ions (H+) forms perchloric acid. The name is perchloric acid and the formula is \(\text{HClO}_4\).

Derive the acid name and formula from nitrate

Nitrate is \(\text{NO}_3^-\). Adding hydrogen ions forms nitric acid. The name is nitric acid and the formula is \(\text{HNO}_3\).

Derive the acid name and formula from bromite

Bromite is \(\text{BrO}_2^-\). Adding hydrogen ions forms bromous acid. The name is bromous acid and the formula is \(\text{HBrO}_2\).

Derive the acid name and formula from dihydrogen phosphate

The dihydrogen phosphate anion is \(\text{H}_2\text{PO}_4^-\). Its corresponding acid is phosphoric acid with an additional hydrogen, giving dihydrogen phosphate the name phosphoric acid and the formula \(\text{H}_3\text{PO}_4\).

Key concepts

perchloric acid

Perchloric acid is an example of an acid derived from the perchlorate ion. Perchlorate, represented as \(\text{ClO}_4^-\), gains hydrogen ions (H\(^+\)) to form the acid. When naming acids formed from 'ate' anions, remember to change the suffix to '-ic'. Thus, the name becomes perchloric acid. Its chemical formula is \(\text{HClO}_4\).
Perchloric acid is a very strong acid and is highly reactive, making it useful in analytical chemistry for etching and cleaning applications. Always handle with care, as it can be dangerous.

nitric acid

Nitric acid is derived from the nitrate ion, denoted as \(\text{NO}_3^-\). When converting nitrate to its corresponding acid, we add hydrogen ions, resulting in nitric acid with the formula \(\text{HNO}_3\).
This acid is important in various industrial applications, such as in the production of fertilizers and explosives. It’s also used in laboratories for metal etching and in the preparation of various organic and inorganic nitrates. Remember, nitric acid is highly corrosive and should be handled with appropriate safety measures.

bromous acid

Bromous acid comes from the bromite ion, \(\text{BrO}_2^-\). Adding hydrogen ions to bromite produces bromous acid, giving it the formula \(\text{HBrO}_2\).
Bromous acid is less commonly discussed compared to other acids like nitric or sulfuric acid. However, it follows the same naming rule for 'ite' anions, which change the suffix to '-ous'.
Always ensure you understand the behaviour and reactivity of less common acids like bromous acid before using them in any practical applications.

phosphoric acid

Phosphoric acid is derived from the dihydrogen phosphate anion, \(\text{H}_2\text{PO}_4^-\). When this anion gains an additional hydrogen ion, it forms phosphoric acid, which has the formula \(\text{H}_3\text{PO}_4\).
Phosphoric acid is widely used in agriculture as a fertilizer. It is also present in soft drinks, acting as a tart-tasting preservative. On top of that, it plays a significant role in rust removal agents and cleaning products.
Always check the concentration of phosphoric acid and handle it properly, particularly in its industrial form, which can be very strong.