Different ways of using phosphoric acid

Even a person who is not keen on chemistry, it is useful to know the properties of some compounds. And among them there are those that can be applied in various fields. For example, phosphoric acid is used in industry and in everyday life. Learn all the ways to apply.

What is it?

What is orthophosphoric acid? It is a compound of inorganic nature, having an average strength. The chemical formula is: H3PO4. Under normal conditions, the acid looks like small crystals that have a rhomboid shape and dissolve fairly quickly in water. Most often, the compound is presented in the form of a solution with a concentration of the basic substance equal to 85%. It is rather thick, almost transparent and has no sharp characteristic odor.

The preparation of orthophosphoric acid can be carried out in several ways:

  1. The combustion of phosphorus under the influence of oxygen, at which the interaction of phosphorus oxide with water molecules begins.
  2. Hydrolysis of the original substance - phosphorus pentachloride.
  3. Conversion from phosphate.
  4. Extraction during the decomposition of natural phosphates under the influence of hydrochloric acid.
  5. The reaction of white phosphorus and dilute non-concentrated hydrochloric acid.

Main characteristics

Phosphoric acid has the following characteristics:

  • Interaction with strong highly concentrated acids provokes the manifestation of signs of amphotericity. Salts of phosphoryl begin to form.
  • The compound has good solubility in water, alcohol solutions and various solvents.
  • When heated to 215 degrees and above, conversion to pyrophosphoric acid occurs.
  • In concentrated solutions and in a molten form, the acid is distinguished by a high viscosity, due to the formation of strong hydrogen intermolecular bonds.
  • In aqueous solutions, the process of electrolytic dissociation starts, which passes through three stages and leads to the isolation of the hydroxonium cation. The degree of reaction and type are set by the level of acidity of the solution.
  • Contact with amorphous hydroxides and bases leads to the release of salt and water.
  • Thermal decomposition to another compound - diphosphoric acid.
  • A characteristic feature and the main difference from other phosphoric acids is the reaction with silver nitrate. The result is a yellow precipitate.
  • Interacting with bases, salts of weak acids, some metals, ammonia, basic oxides.

Various applications

How can the compound be used? Orthophosphoric acid is used in various fields, and all of them will be considered in detail.


Phosphoric acid has been used in the oil industry, it is included in the film and matches. But especially often and effectively, the connection is used in metallurgy, because it provides protection from corrosion, is included in primers for metal surfaces, performs flux functions during soldering, cleans and polishes metal products, and is used for anticorrosion treatment in order to extend the life of parts. In addition, orthophosphoric acid is part of the wood impregnation imparting fireproof properties to this material.Similar solutions are also applicable in textile production to improve the quality of the fabric. And in aviation, acid is used to produce hydrofluids.

Food production

Food orthophosphoric acid is designated as E338 and is part of some food products. It prolongs shelf life and prevents damage and decay, prevents the appearance of extraneous flavors (sour, bitter), regulates the level of acidity and slows oxidation, helps to preserve the taste or gives a light sour taste.

E338 additive can be seen in carbonated drinks, semi-finished products, sausage and meat products, cheeses (especially processed), sweeteners, baking powder (baking powder for dough), confectionery and bakery products.

For your information: In many countries orthophosphoric acid is not included in the ban list, but should be used in minimal quantities.

Biology and Medicine

In medicine, the compound is used mainly in dentistry, and for several purposes at once. So, it is used by dentists for etching tooth enamel before the procedure of dental fillings.This allows you to increase the adhesion of the filling material with tissues, but the specialist cannot determine the degree of processing and control the complete removal of the compound from the enamel. If the acid remains in the tooth, it can reduce its density and begin the process of destruction. The compound is also included in the composition of the so-called dental cement, some drugs and bleaching agents.

In biology, the substance is used for conducting various studies, catalyzing organic synthesis, and making reagents. Orthophosphoric acid has been used in pharmacology for the production of drugs.

Life and agriculture

Phosphoric acid is widely and for various purposes used in everyday life and agricultural activities. Here are the main areas:

  • production of household chemicals, concentrated cleaning products, coping with heavy pollution;
  • control of rust;
  • production of phosphate fertilizers for plants;
  • veterinary medicine (for example, treatment of urolithiasis in some animals);
  • production of refrigeration units (acid is a binder component in obtaining coolant - freon).

Is it possible to use it yourself at home?

Independent use of orthophosphoric acid is not highly recommended due to the toxicity of the compound. But still some take the risk and use the compound at home. There are three ways: dipping a metal product into a solution to rust, spraying the substance or treating the surface after a mechanical cleaning.

Work with orthophosphoric acid is possible only in a well-ventilated room, in a protective suit, respirator, gloves and glasses. Do not allow the substance to come into contact with the skin and mucous membranes, inhalation of vapors is also dangerous.

Important! It is better not to try to start self-application in order to avoid serious consequences.

Effects on the human body

With regular ingestion of food acid in the body and exceeding its doses, a negative effect is possible in the form of increased acidity, development of diseases of the gastrointestinal tract, destruction of tooth enamel, disruption of acid-base balance, decrease in bone density (this is called osteoporosis) and other negative consequences . Careless work with industrial orthophosphoric acid can lead to severe skin burns. Inhalation of fumes is extremely dangerous.

Phosphoric acid is a widely used compound with a mass of beneficial properties. But it can only be used in special conditions and by professionals.

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