The use of orthophosphoric acid in everyday life, agriculture and the food industry - chemical properties

• Characteristics
• Areas of application
• Operating rules
• Anti-rust application
• Application for metal

Often metal and products made from it are subject to a characteristic “disease”, which manifests itself in the form of a red coating that corrodes the metal. We're talking about rust. Its formation occurs due to the effect of carbon dioxide, oxygen and water on the surface of a metal product. Of course, in order to extend the life of a metal product, it is necessary to begin the fight against corrosion as soon as possible. Treatment with phosphoric acid can help with this.

What is phosphoric acid

At room temperature these are hygroscopic, colorless, diamond-shaped crystals that are highly soluble in water. An orthophosphoric compound is considered an inorganic acid of medium strength. One of its forms is a yellowish or colorless syrupy liquid, odorless, an aqueous solution with a concentration of 85%. Its other name is white phosphoric acid.

The chemical orthophosphorus compound has the following properties:

• soluble in ethanol, water, solvents;
• forms 3 rows of salts - phosphates;
• causes burns upon contact with skin;
• when interacting with metals, it forms flammable, explosive hydrogen;
• the boiling point depends on the concentration - from 103 to 380 degrees;
• the liquid form is prone to hypothermia;
• incompatible with flammable materials, pure metals, quicklime, alcohol, calcium carbide, chlorates;
• at a temperature of 42.35 degrees it melts, but does not decompose.

When is it necessary to adjust the pH value of a nutrient solution?

In hydroponics, pH adjustment is usually done in three cases:

1) when preparing a nutrient solution of normal concentration for direct use (which in English is called the final solution

);
2) when preparing a nutrient solution concentrate for long-term storage (which in English is called stock solution
); 3) when the acidity of the nutrient solution poured into the container changes significantly over time (for example, by 0.5 or 1 pH unit or more per day).

Formula

Phosphoric acid is an inorganic compound that is described by the formula H3PO4. Its molar mass is 98 g/mol. A microparticle of a substance is built in space in such a way that it connects hydrogen and oxygen atoms with each other. The formula shows that the chemical substance has the following composition:

Preparation of phosphoric acid

A chemical compound has several production methods. The well-known industrial method for producing phosphoric acid is thermal, which produces a pure, high-quality product. The following process occurs:

• oxidation during combustion with excess air of phosphorus to phosphorus anhydride having the formula P4O10;
• hydration, absorption of the resulting substance;
• condensation of phosphoric acid;
• capturing mist from the gas fraction.

There are two more methods for producing orthophosphorus compounds:

• An economical extraction method. Its basis is the decomposition of natural phosphate minerals with hydrochloric acid.
• Under laboratory conditions, the substance is obtained by reacting white phosphorus, which is toxic, with dilute nitric acid. The process requires strict adherence to safety precautions.

Recommendations

1. Harwood, Lawrence M.; Hodgkinson, Leslie C.; Sutherland, James K.; Towers, Patrick (1984). “Synthesis of anthracyclines. Part 1. Regioselective alkylation of 5-hydroxyquinisarine." Canadian Journal of Chemistry
   .
   62
   (10): 1922–1925. Doi:10.1139/v84-329.
2. Nakazawa, Koichi; Matsuura, Shin; Kusuda, Kosuke (1954). “Research on the use of polyphosphoric acid as a condensing agent. II". Yakugaku Zasshi
   .
   74
   (5):495–497. doi:10.1248/yakushi1947.74.5_495.
3. "Phosphoric acid and phosphates." Encyclopedia of Chemical Technology
   . New York: Interscience Encyclopedia, Inc., 1953. p. 421.
4. "Polyphosphates for protection against scale and corrosion." Tramfloc, INC. January 2009. Retrieved December 23, 2010.
5. "Ortho-polyphosphate corrosion inhibitors" (PDF). Government Engineering: A Journal of Public Infrastructure
   (September–October 2006): 48–49. Retrieved December 23, 2010.
6. Parmar, Dixit; Sugiono, Early; Raja, Sadia; Ruping, Magnus (2014). “A Complete Guide to Asymmetric Acid BINOL Phosphate and Metal Catalysis: History and Classification by Mode of Activation; Bronsted acidity, hydrogen bonding, ion pairing and metal phosphates.” Chemical Reviews
   .
   114
   (18):9047–9153. Doi:10.1021/cr5001496. PMID 25203602.

Chemical properties

The inorganic compound is considered tribasic and of medium strength. The following chemical properties of orthophosphoric acid are characteristic:

• reacts to indicators by changing color to red;
• when heated, it is converted to pyrophosphoric acid;
• in aqueous solutions undergoes three-stage dissociation;
• when reacting with strong acids, it forms phosphoryls - complex salts;
• forms a yellow precipitate when interacting with silver nitrate;
• thermally decomposes to diphosphoric acid;
• upon contact with bases, amorphous hydroxides, it forms water and salt.

Application

Phosphoric acid is used in many areas, from industry to dental treatment. The product is used by craftsmen as a flux when soldering, to clean the metal surface from rust. Liquid is used:

• for scientific research in molecular biology;
• as a catalyst for organic synthesis processes;
• for creating anti-corrosion coatings on metals;
• in the production of fire-resistant impregnations for wood.

The substance is used:

• in the oil industry;
• in the manufacture of matches;
• for film production;
• for the purpose of protection against corrosion;
• to clarify sucrose;
• in the manufacture of medicines;
• in refrigeration units as a binder in freon;
• during mechanical processing for polishing and cleaning metals;
• in the textile industry in the production of fabrics with fire retardant impregnation;
• as a component in the production of chemical reagents;
• in veterinary medicine for the treatment of urolithiasis in minks;
• as a component for metal primer.

In the food industry

The use of phosphoric acid in food production has become widespread. It is registered in the register of food additives under code E338. When consumed in acceptable quantities, the substance is considered safe. The following properties of the drug are useful:

• preventing rancidity;
• acidity regulation;
• shelf life extension;
• preservation of taste characteristics;
• enhancing the effect of antioxidants.

Phosphoric acid as an acidifier, leavening agent, and antioxidant is used in the bakery, meat, and dairy industries. Used in the production of confectionery and sugar. The substance gives products a sour, bitter taste. Additive E338 is included in:

• processed cheeses;
• muffins;
• carbonated drinks - Pepsi-Cola, Sprite;
• sausages;
• buns;
• milk;
• baby food;
• marmalade;
• cakes

Research has shown that overconsumption of products containing phosphorus compounds, especially carbonated drinks, can lead to health problems. It is possible:

• leaching of calcium from the body, which can trigger the formation of osteoporosis;
• violation of the acid-base balance - the additive can increase its acidity;
• the appearance of gastrointestinal diseases;
• exacerbation of gastritis;
• destruction of tooth enamel;
• development of caries;
• the appearance of vomiting.

In the non-food industry

The use of phosphoric acid can be observed in many areas of production. This is often due to the chemical properties of the product. The drug is used for the manufacture of:

• combined, phosphorus mineral fertilizers;
• activated carbon;
• phosphorus salts of sodium, ammonium, manganese;
• fire retardant paints;
• glass, ceramics;
• synthetic detergents;
• fire-resistant binding components;
• non-flammable phosphate foam;
• hydraulic fluids for the aviation industry.

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In medicine

Dentists use orthophosphorus composition to treat the inner surface of the crown. This helps improve its adhesion to the tooth during prosthetics. The substance is used by pharmacists to prepare medicines and dental cement. In medicine, the use of orthophosphorus compounds is associated with the ability to etch tooth enamel. This is necessary when using adhesive materials of the second or third generation for filling. Important points - after etching the surface it is necessary to:

• Rinse;
• dry.

Main signs of pancreatic enzyme deficiency

Identifying enzyme deficiencies is quite simple. The key symptoms are heaviness after eating, a feeling of fullness in the abdomen and abdominal discomfort. Often these symptoms are accompanied by bloating, rumbling, flatulence, and diarrhea. Most often, such symptoms can occur in ordinary situations: when eating heavy, fatty foods or when overeating, when it was simply impossible to resist eating a lot of tasty dishes. In this case, you should not be afraid of problems with the pancreas or other gastrointestinal diseases. The pancreas simply cannot cope with much work and may need help.

Why does diarrhea occur? Fats are the most difficult components of food to digest. If there is a lack of enzymes in the body, it is with the processing of fats that difficulties arise. As a result, undigested fats that are not decomposed by enzymes contribute to a change in the nature of the stool and the rapid movement of contents along the intestines, which provokes diarrhea8.

If a lack of enzymes and digestive problems persist for a long time, then this does not go unnoticed by the body. Symptoms may worsen and become regular rather than episodic. Constant diarrhea gives rise to vitamin deficiency; protein-energy deficiency and dehydration throughout the body can develop. Significant weight loss may occur. In addition, in severe stages, the following symptoms of pancreatic enzyme deficiency may be observed8:

• nausea and vomiting;
• heartburn;
• a sharp decrease in appetite;
• general weakness.

Anti-rust application

A rust converter based on phosphoric acid creates a protective layer on the surface that protects against corrosion during further use. The peculiarity of using the compound is that it is safe for metal when applied. There are several ways to remove rust with phosphoric acid, depending on the size of the damage:

• etching with immersion in a bath or other container;
• repeated application of the composition to the metal with a spray gun or roller;
• covering the surface with pre-treated mechanical cleaning.

The orthophosphorus compound converts rust into iron phosphates. The composition can be used for washing and cleaning:

• rolled metal products;
• wells;
• pipeline surfaces;
• steam generators;
• water supply, heating systems;
• coils;
• boilers;
• water heaters;
• heat exchangers;
• boilers;
• machine parts and mechanisms.

How does it work

The process is simple. You buy a converter; it usually comes in spray cans. Next, it is sprayed onto the site of the outbreak, then it is advisable for us to leave this place for about half an hour - an hour.

The product does not remove rust at all, if I may put it roughly, it freezes it and prevents it from spreading further. An iron phosphate film forms on the affected surface, which is a protective element. The work period is approximately one to two years, then it is advisable to repeat the procedure.

I would like to note from personal experience that my uncle is a minibus taxi driver and works on his minibus almost every season before winter. And you know, it really rots less when compared with untreated neighboring cars along the route.

But we are wondering whether it is possible to produce it with our own hands, what is the approximate composition. I’ll say right away that there are two compositions, the one that is used in production, and the one that is made at home.

Interaction of phosphoric acid

The properties of an inorganic substance determine its interaction with other substances and compounds. In this case, chemical reactions occur. The orthophosphorus composition interacts with:

• salts of weak acids;
• hydroxides, entering into a neutralization reaction;
• metals to the left of hydrogen in the activity series with the formation of salt and the release of hydrogen;
• basic oxides, participating in the exchange reaction;
• ammonium hydroxide, creating ammonium hydrogen phosphate;
• ammonia to produce acid salts.

external reference

• Determination of polyphosphates using ion chromatography with suppressed conductivity detection, instructions for use 71 from Dionex
• USA 3044851

Safety precautions when working with acid

Orthophosphorus compound belongs to the class of hazardous substances and requires caution. Work with the composition must be carried out in a special room equipped with supply and exhaust ventilation, away from sources of fire. The lack of personal protective equipment is unacceptable:

• respirator;
• gloves;
• special clothing;
• non-slip shoes;
• points.

Contact of orthophosphorus composition on the skin or eyes is dangerous, and inhalation of hot vapors is harmful. This may cause burns, dizziness, vomiting, and coughing. In case of emergency you need to:

• remove clothing that has come into contact with the substance;
• rinse the affected area with running water;
• call a doctor;
• apply a loose bandage;
• Neutralize spilled liquid with alkali.

Transportation rules

There are special GOSTs that stipulate the rules for transporting phosphoric acid, which is classified as dangerous goods. The substance can be delivered by any type of transport. The chemically active liquid is transported in tightly closed:

• steel tank trucks;
• bottles made of polyethylene, glass;
• plastic cubes;
• barrels;
• cans;
• rubberized railway tanks.

Price

Phosphoric acid can be purchased in pharmacies, hardware stores, and ordered through Internet sites. For industrial purposes, they are purchased in bulk at discounts. The average cost for Moscow in rubles is: