# Phosphorous Acid

Phosphorous Acid is a yellow or white crystalline acid or an odorless, colorless phosphorous-containing inorganic acid. It acts as an intermediate in the preparation of other phosphorus acids. It is used as orthodontics as an etching solution. It is used in the dental appliance to clean surfaces of the teeth. Phosphorous acid plays a vital role in metabolism as it is a constituent in teeth and bone.

Phosphorous acid is termed as orthophosphoric acid. When an unstable element readily absorb moisture it is converted into phosphoric acid when it is heated above one eight degree Celsius. The salts that are formed by phosphoric acid are called phosphites. They are used in crops to reduce or encounter fungi like pathogens.

## Phosphite Salts and Phosphorous Acid

The best method to prepare phosphorous acid is by hydrolysis of phosphorous hydroxide. In the below equation the resulting equation is heated resulting in eradicating HCL.

$PCl_{3}+3H_{2}O ightarrow H_{3}PO_{3}+3HCL$

Rest of the water is evaporated until the phosphorous acid that is colorless crystalline appears on cooling. At 158.2 °F, the colorless crystalline phosphoric acid melts, as a result, it is readily soluble in water and comprises of an odor that is similar to that of garlic. When phosphorous acid is heated above two hundred degree Celsius (200 °C), it disproportionate into phosphine.

$4H_{3}PO_{3}+heat ightarrow PH_{3}+3H_{3}PO_{4}$

The salts of the phosphoric acid act as an active reducing agent. For instance, phosphorous acid reduces mercury salts (||) to mercury (|).

### Uses of Phosphoric Acid

They are used in the preparation of potassium phosphite which is a phosphite salt. It is used commonly as a rest removal. Phosphorous are found in various food products such as egg yolks, nuts, fish, milk, meat, and poultry. Phosphorous acid is mainly used in the production of phosphonates that are employed in the water treatment.

#### Practise This Question

Choose correct option-
OptionArtifical SweetenerSweetness value in comparison to cane sugara)Saccharin200b) Aspartame 1000c) Alitame 2000d) Sucralose 500