Differentiate between phosphoric acid and hypophosphoric acid

In the field of chemistry, there are many acids. Phosphoric acid and hypophosphoric acid are often confused, so it is necessary to distinguish them in detail.

Phosphoric acid, its chemical formula is\ (H_3PO_3\). In the molecular structure, the phosphorus atom is connected to three hydroxyl groups, and there is a hydrogen atom directly connected to the phosphorus atom. Its properties are unique, although it is a dibasic acid, it has strong reducing properties. In chemical reactions, silver ions can be reduced to silver elementals, which is one of its remarkable characteristics.

Hypophosphoric acid, the chemical formula is\ (H_3PO_2\). In the molecular structure, phosphorus atoms are only connected to one hydroxyl group, but there are two hydrogen atoms directly connected to phosphorus atoms. Hypophosphoric acid is a monogenic acid, but its reductivity is more prominent than that of phosphoric acid. It can reduce the copper sulfate solution under certain conditions and precipitate metallic copper.

The two are also different in physical properties. Phosphoric acid is usually a colorless crystal, hygroscopic and easily soluble in water. Hypophosphoric acid is a colorless oily liquid or deliquescent crystal, which is also easily soluble in water.

Looking at its chemical properties, phosphoric acid under heating conditions will undergo a disproportionation reaction to form phosphoric acid and phosphine. And phosphoric acid is decomposed into phosphine and phosphoric acid when heated.

In practical applications, phosphoric acid is often used as a reducing agent, nylon whitening agent, etc. Hypophosphoric acid is mostly used for electroless nickel plating, which can form a uniform coating on the metal surface and enhance the corrosion resistance and wear resistance of the metal.

To distinguish phosphoric acid from hypophosphoric acid, it is necessary to observe its molecular structure, chemical properties, physical properties and applications in order to clearly distinguish and avoid confusion.