Phosphoric acid

A mineral acid with the chemical formula H₃PO₄

Phosphoric acid

IUPAC Name:	Phosphoric acid
Other Names:	Orthophosphoric acid
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Chemical formula	CHNO
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Phosphoric acid is a mineral acid with the chemical formula H₃PO₄. It is a non-toxic acid that is commonly used in various industrial and food applications. Phosphoric acid is a key ingredient in many fertilizers, detergents, and food additives.

Structure and Properties

Phosphoric acid is a triprotic acid, meaning it can donate three protons (H⁺ ions). Its molecular structure consists of a central phosphorus atom surrounded by four oxygen atoms, forming a tetrahedral arrangement. The chemical structure can be represented as O=P(OH)₃.

The acid is typically found as a colorless, odorless solid or as a viscous liquid. It is highly soluble in water, forming an acidic solution. The acid dissociates in water to form dihydrogen phosphate (H₂PO₄⁻), hydrogen phosphate (HPO₄²⁻), and phosphate (PO₄³⁻) ions, depending on the pH of the solution.

Production

Phosphoric acid is primarily produced by two methods: the wet process and the thermal process.

• Wet Process: This method involves the reaction of sulfuric acid with phosphate rock to produce phosphoric acid and calcium sulfate (gypsum) as a by-product. This is the most common method for producing phosphoric acid for fertilizer use.

• Thermal Process: In this method, elemental phosphorus is burned in air to produce phosphorus pentoxide, which is then hydrated to form phosphoric acid. This process yields a purer product and is used for food-grade phosphoric acid.

Applications

Phosphoric acid has a wide range of applications:

• Fertilizers: It is a key component in the production of phosphate fertilizers, which are essential for modern agriculture.

• Food Industry: Used as an acidulant in soft drinks and other food products to provide a tangy flavor.

• Cleaning Agents: Employed in rust removal and as a cleaning agent for metals.

• Dental and Orthopedic Applications: Used in dentistry as an etching solution and in orthopedic surgery as a component of bone cements.

Health and Safety

Phosphoric acid is considered non-toxic, but it is corrosive and can cause irritation to the skin, eyes, and respiratory tract. Proper handling and safety precautions should be observed when working with this chemical.

Also see

• Sulfuric acid
• Nitric acid
• Hydrochloric acid
• Phosphate
• Fertilizer