Phosphoric acid is a white or colorless, odorless, viscous liquid or solid with the formula H3PO4. Phosphoric acid, a strong acid, is used in many fields in industry and daily life. Phosphoric acid, the most important compound of the element phosphorus, is used to produce phosphate salts. The chemical and physical properties of phosphoric acid are as follows:

• Its molecular weight is 98 g/mol.
• Its melting point is 42.35 °C.
• Boiling point is 213 °C.
• Its density is 1.885 g/mL.
• Solubility is high in water and alcohol, low in ether.

The production methods of phosphoric acid are as follows:

• Sulfuric acid method: This is the most common production method of phosphoric acid. Phosphoric acid is obtained by reacting phosphate rocks with sulfuric acid. This method also produces calcium sulphate.
• Thermal method: This is the purest production method of phosphoric acid. Phosphoric acid is obtained by burning phosphorus in a mixture of air and steam. This method also produces phosphorus oxide.
• Lime method: This is an alternative production method of phosphoric acid. Phosphoric acid is obtained by reaction of sodium carbonate solution with lime (calcium hydroxide). This method also produces sodium hydroxide.

Uses of phosphoric acid include the following:

• Agriculture and fertilizer production: Phosphoric acid is used in the production of fertilizers in the agricultural sector. Phosphorus is an essential nutrient for the growth and development of plants. Phosphoric acid can be used in the production of phosphorus-containing fertilizers to improve soil fertility.
• Food and beverage industry: Phosphoric acid is used as an acidity regulator in food and beverages. It is especially preferred in soft drinks (cola, fruit juices, carbonated drinks) and processed foods to provide a balanced taste with sweeteners.
• Chemical industry: Phosphoric acid is used as a catalyst or intermediate in organic synthesis and chemical reactions. It can also be used in anti-rust coatings of metal surfaces and in paint production.
• Metal cleaning and rust removal: Phosphoric acid is used as an effective agent for rust removal and cleaning of metal surfaces. When applied to metal surfaces, it helps dissolve rust and provides a clean surface.
• Dentistry and oral care products: Phosphoric acid is used in dentistry and oral care products. It is especially used in bonding processes to prepare tooth enamel.
• Water treatment: Phosphoric acid is used to adjust the phosphorus solution in water treatment processes. It is an important chemical for phosphorus control, especially in wastewater treatment plants.
• Metal surface coatings: Phosphoric acid is used as one of the key components of anti-rust coatings for metal surfaces. It is used to increase the corrosion resistance of metal surfaces.