Orthophosphoric acid

Orthophosphoric acid (also known as Phosphoric acid) is a non-toxic acid, which, when pure, is a solid at room temperature and pressure. The chemical formula for orthophosphoric acid is H3PO4 and it is most commonly found in an aqueous form.

Chemical Properties

Orthophosphoric acid is a weak acid with a pKa of 2.15. It is completely soluble in water and is commonly used in laboratories for pH adjustment. The acid is a triprotic acid, meaning it can donate up to three protons (H+ ions) per molecule in reactions.

Production

Orthophosphoric acid is produced from naturally occurring phosphate rock. The rock is ground and mixed with sulfuric acid and water, then heated to produce phosphoric acid. This process is known as the wet process because it involves a significant amount of water.

Uses

Orthophosphoric acid has a wide range of uses. It is used in the production of fertilizers, detergents, and pharmaceuticals. It is also used in the food industry as a food additive and flavoring agent, particularly in carbonated beverages. In dentistry, orthophosphoric acid is used as an etching solution to clean and roughen the surfaces of teeth before the application of fillings or sealants.

Safety

While orthophosphoric acid is non-toxic, it can cause irritation to the skin and eyes. It is recommended to use personal protective equipment when handling this chemical.

See Also

• Phosphoric acids
• Phosphate
• Phosphorus