7664-38-2

A clear colorless liquid or transparent crystalline solid. The pure solid melts at 42.35°C and has a density of 1.834 g/cm3. Liquid is usually an 85% aqueous solution. Shipped as both a solid and liquid. Corrosive to metals and tissue. Used in making fertilizers and detergents and in food processing.

PHOSPHORIC ACID(7664-38-2) reacts exothermically with bases. May react with active metals, including such structural metals as aluminum and iron, to release hydrogen, a flammable gas. Can initiate the polymerization of certain classes of organic compounds. Reacts with cyanide compounds to release gaseous hydrogen cyanide. May generate flammable and/or toxic gases in contact with dithiocarbamates, isocyanates, mercaptans, nitrides, nitriles, sulfides, and strong reducing agents. Forms explosive mixture with nitromethane. Reacts violently with sodium tetrahydroborate. In the presence of chlorides can corrode stainless steel to form explosive hydrogen gas. Emits toxic and irritating fumes of oxides of phosphorus when heated to decomposition [Lewis, 3rd ed., 1993, p. 1029].

Soluble in water with small release of heat.

Burns on mouth and lips, sour acrid taste, severe gastrointestinal irritation, nausea, vomiting, bloody diarrhea, difficult swallowing, severe abdominal pains, thirst, acidemia, difficult breathing, convulsions, collapse, shock, death.

Phosphoric acid is used in the manufacture of fertilizers, phosphate salts; polyphosphates, detergents, activated carbon; animal feed; ceramics, dental cement; pharmaceuticals, soft drinks; gelatin, rust inhibitors; wax, and rubber latex. Exposure may also occur during electropolishing, engraving, photoengraving, lithographing, metal cleaning; sugar refining; and water-treating.

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; give artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. For minor skin contact, avoid spreading material on unaffected skin. Keep victim warm and quiet. Effects of exposure (inhalation, ingestion or skin contact) to substance may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. Medical observation is recommended for 24
48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consider administering a drug or other inhalation therapy.

UN1805 Phosphoric acid solution, Hazard class: 8; Labels: 8-Corrosive material. UN3543 Phosphoric acid solid, Hazard class: 8; Labels: 8-Corrosive material.

The substance is a medium strong acid. Incompatible with strong caustics; most metals. Readily attacks and reacts with metals forming flammable hydrogen gas. Do not mix with solutions containing bleach or ammonia. Violently polymerizes on contact with azo compounds; epoxides, and other polymerizable compounds. Decomposes on contact with metals, alcohols, aldehydes, cyanides, ketones, phenols, esters, sulfides, halogenated organics; producing toxic fumes. Corrosive to common metals and possibly to some rubbers and plastics.

Phosphoric acid is a colorless, odorless, crystalline solid or a thick syrupy liquid. Physical state is strength and temperature dependent.
Concentrated phosphoric acid occurs as a colorless, odorless, syrupy liquid. It has a pleasing acid taste when suitably diluted.
Pure phosphoric acid, also called orthophosphoric acid, is a clear, colorless, mineral acid with moderate strength. It is normally marketed as an aqueous solution of 75–85% in which it exists as a clear, viscous liquid.

Food-grade phosphoric acid is used to acidify foods and beverages. It provides a tangy or sour taste and, being a mass-produced chemical, is available cheaply and in large quantities. Phosphoric acid, used in many soft drinks, has been linked to lower bone density in epidemiological studies. In brief, phosphoric acid is a strong acid and common industrial chemical used in the manufacture of a wide number of products, notably porcelain and metal cleaners, detergents, and fertilisers. It is also used as a food additive and is a major constituent of many soft drinks. Low phosphate concentrations are found in drinking water to which it is added in some areas in order to reduce lead solubility.

Add slowly to solution of soda ash and slaked lime with stirring, then flush to sewer with large volumes of water.

Chemists refer to orthophosphoric acid as phosphoric acid, which is the IUPAC name for this compound. The prefix “ortho” is used to distinguish the acid from other phosphoric acids, which are generally called polyphosphoric acids. Orthophosphoric acid is a nontoxic, rather weak triprotic acid. When pure, it is a solid at STP. Orthophosphoric acid is a very polar molecule which makes it highly soluble in water. The valence state of phosphorous in orthophosphoric acid and other phosphoric acids is ＋5. Triprotic means that the orthophosphoric acid molecule can dissociate up to three times, producing a hydrogen cation, H⁺, each time.

Phosphoric acid is a natural constituent of many fruits and their juices.

Phosphoric acid was produced but not identified by alchemists in ancient times. It derives its name from the element phosphorus, which was discovered in 1669 by Henning Brand (1630 1710).Scheele subsequently isolated phosphorus from bone ash and produced phosphoric acid by reacting phosphorus and nitric acid. Scheele's method replaced bone as the main source of phosphorus rather than urine.
John Bennett Lawes (1814 1900) patented a process in 1841 of making superphosphate from bones and later extended his process to phosphates obtained from rock. Superphosphates are made by treating Ca3(PO4)2 with sulfuric acid to make more soluble calcium hydrogen phosphates: Ca3(PO4)2 + 2H2SO4 Ca(H2PO4)2 + 2CaSO4. In this reaction Ca(H2PO4)2 is monobasic calcium phosphate, which is also called superphosphate. Calcium hydrogen phosphates (superphosphates) are more water soluble and therefore more readily available to plants.

ChEBI: A phosphorus oxoacid that consits of one oxo and three hydroxy groups joined covalently to a central phosphorus atom.

The major sources of H3PO4 traditionally have been mineral deposits of phosphate rock. Mining operations are extensive in a number of locations, including the United States (Florida), the Mediterranean area, and Russia, among others. The major constituent of most phosphate rocks is fluorapatite, 3Ca3(PO4)2·CaF2. The supply of high-grade phosphates, the raw material of choice for producing high-purity phosphoric acid by the wet process, is rapidly decreasing in some areas.
Two major methods are utilized for the production of phosphoric acid from phosphate rock. The wet process involves the reaction of phosphate rock with sulfuric acid to produce phosphoric acid and insoluble calcium sulfates. Many of the impurities present in the phosphate rock are also solubilized and retained in the acid so produced. While they are of no serious disadvantage when the acid is to be used for fertilizer manufacture, their presence makes the product unsuitable for the preparation of phosphatic chemicals.
In the other method, the furnace process, phosphate rock is combined with coke and silica and reduced at high temperature in an electric furnace, followed by condensation of elemental phosphorus. Phosphoric acid is produced by burning the elemental phosphorus with air and absorbing the P2O5 in water. The acid produced by this method is of high purity and suitable for nearly all uses with little or no further treatment.

The majority of phosphoric acid is made by digesting phosphate rock (essentially tricalcium phosphate) with sulfuric acid; the phosphoric acid is then separated by slurry filtration. Purification is achieved via chemical precipitation, solvent extraction, crystallization, or ion exchange.

Pharmaceutic aid (solvent).

Phosphoric acid is water soluble and absorbs oxygen readily, and the specific gravity is 1.89, which is heavier than water. It is toxic by ingestion and inhalation and an irritant to the skin and eyes, with a TLV of 1 mg/m3 of air. The four-digit UN identification number is 1805. The NFPA 704 designation is health 3, flammability 0, and reactivity 0. The primary use of phosphoric acid is in chemical analysis and as a reducing agent.

Nonflammable

Phosphoric acid (H₃PO₄), also known as orthophosphoric acid, is the most significant source of phosphate fertilizers. Phosphoric acid based fertilizers mainly include ammonium phosphate, diammonium phosphate and monoammonium phosphate.
Phosphoric acid is deliquescent and commercially the most important derivative of phosphorus, accounting for over 90% of the phosphate rock mined. The white rhombic solid is highly soluble in water and ethanol, and the concentrated aqueous solution is generally available for use.
Phosphoric acid is used in several industries other than the fertilizer industry. Most elemental phosphorus is converted into phosphoric acid for non-fertilizer use. There are two basic processes for the production of phosphoric acid.
Metaphosphoric acid is obtained by heating phosphoric acid until dense white fumes begin to appear. The product is highly deliquescent and glassy in appearance. Its salts are known as metaphosphates. Orthophosphoric acid is the most common and is used as an important phosphate ingredient in commercial fertilizers.

Phosphoric acid is widely used as an acidifying agent in a variety of pharmaceutical formulations. It is used in pharmaceutical products as part of a buffer system when combined with a phosphate salt such as sodium phosphate, monobasic or dibasic. It is also widely used in food preparations as an acidulant, flavor, and synergistic antioxidant (0.001–0.005%) and sequestrant.
Therapeutically, dilute phosphoric acid has been used welldiluted in preparations used in the treatment of nausea and vomiting. Phosphoric acid 35% gel has also been used to etch tooth enamel and to enhance delivery of drugs through the nail.
) Nanosized hydroxyapatite powder was made by combining phosphoric acid with egg shells.

As a cleanser for metals, phosphoric acid produces a light etch on steel, aluminum, or zinc, which aids paint adhesion. Deoxidine is a phosphoric acid cleanser for metals. Nielite D is phosphoric acid with a rust inhibitor, used as a nonfuming pickling acid for steel. Albrite is available in 75, 80, and 85% concentrations in food and electronic grades, both high-purity specifications. DAB and Phosbrite are called Bright Dip grades, for cleaning applications. Phosphoric anhydride, or phosphorus pentoxide, P2O5, is a white, water-soluble powder used as a dehydrating agent and also as an opalizer for glass. It is also used as a catalyst in asphalt coatings to prevent softening at elevated temperatures and brittleness at low temperatures.

Phosphoric acid is commonly used in fertilizer industry. It is also used in the manufacture of insecticide and pesticide.

In the concentrated form, phosphoric acid is an extremely corrosive and harmful acid. However, when used in pharmaceutical formulations it is usually very diluted and is generally regarded as an essentially nontoxic and nonirritant material.
The lowest lethal oral dose of concentrated phosphoric acid in humans is reported to be 1286 mL/kg.
(rabbit, skin): 2.74 g/kg
(rat, oral): 1.53 g/kg

The elemental phosphorus is burned to produce phosphorous pentoxide (P2O5), which is then hydrated. The heat is then removed and the phosphoric acid (H3PO4) is collected as a fine mist. Another important source of phosphoric acid is from phosphate rocks by treatment with sulfuric acid; this is the so-called wet-acid process. The synthesis of pure phosphoric acid involves several steps including a time-consuming, expensive step, the sublimation of white phosphorus.

Phosphoric acid was not mutagenic in bacterial assays.

When stored at a low temperature, phosphoric acid may solidify, forming a mass of colorless crystals, comprising the hemihydrate, which melts at 28°C. Phosphoric acid should be stored in an airtight container in a cool, dry place. Stainless steel containers may be used.

GRAS listed. Accepted as a food additive in Europe. Included in the FDA Inactive Ingredients Database (infusions, injections, oral solutions, topical creams, lotions, ointments and solutions, and vaginal preparations). Included in nonparenteral and parenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.