Pyrophosphoric acid

Pyrophosphoric acid (also known as diphosphoric acid) is an acid that has the chemical formula H₄P₂O₇. It is an oxyacid of phosphorus and is a medium-strong inorganic acid.

Properties

Pyrophosphoric acid is a colorless, odorless, hygroscopic and non-volatile substance. It is soluble in water, alcohol, and diethyl ether. It is a tetraprotic acid, meaning it has four replaceable hydrogen atoms.

Preparation

Pyrophosphoric acid can be prepared by heating orthophosphoric acid. The reaction is as follows:

2 H₃PO₄ → H₄P₂O₇ + H₂O

Uses

Pyrophosphoric acid is used in several applications. It is used as a catalyst in the synthesis of ammonia and acetic acid. It is also used in the production of phosphate esters, plasticizers, and phosphate salts. In addition, it is used in the food industry as an emulsifier and buffering agent.

Safety

Pyrophosphoric acid is a corrosive substance and can cause burns if it comes into contact with the skin or eyes. It is also harmful if swallowed or inhaled.

See also

• Phosphoric acid
• Polyphosphoric acid
• Phosphorus pentoxide