The compound H3PO4 is phosphoric acid. As a solid, it is a crystal that is odorless and colorless; as an aqueous solution, it is an odorless, clear liquid.
Phosphoric acid is an ingredient in household cleaners and rust inhibitors. It is used as a dental etching solution and removes plaque from teeth before whitening. In construction, it is used to eliminate hard water stains and mineral deposits. Phosphoric acid is an ingredient in several foods and soft drinks, especially colas, adding acidification and a sour or tangy taste.
Exposure to concentrated forms of phosphoric acid is corrosive to the skin and eyes, and ingesting it causes burns and tissue destruction within the gastrointestinal tract. Inhalation can lead to pulmonary edema or chemical burns in the respiratory tract.