Potassium sulfite is the

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the formula K₂SO₃. It is the

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

cation and

sulfite Sulfites or sulphites are compounds that contain the sulfite ion (systematic name: sulfate(IV) ion), . The sulfite ion is the conjugate base of bisulfite. Although its acid (sulfurous acid) is elusive, its salts are widely used. Sulfites are ...

anion. It is a white solid that is highly soluble in water. Potassium sulfite is used for preserving food and beverages.

History

Potassium sulfite was first obtained by

Georg Ernst Stahl Georg Ernst Stahl (22 October 1659Stahl's date of birth is often given erroneously as 1660. The correct date is recorded in the parish register of St. John's church, Ansbach. See – 24 May 1734) was a German chemist, physician and philosopher. ...

in the early 18th century, and was therefore known afterwards as Stahl's sulphureous salt. It became the first discovered sulfite and was first properly studied along with other sulfites by French chemists in the 1790s, and it was called sulphite of potash in the early 19th century.

Gilles-François Boulduc Gilles-François Boulduc (born 20 February 1675 in Paris; died 17 January 1741 in Palace of Versailles, Versailles) was a French pharmacist and chemist.All but one reference gives 20 February 1675 as the date of birth. The closest reference to this ...

also discovered the salt in water of

Passy Passy () is an area of Paris, France, located in the 16th arrondissement of Paris, 16th arrondissement, on the Rive Droite, Right Bank. It is adjacent to Auteuil, Paris, Auteuil to the southwest, and Chaillot to the northeast. It is home to many ...

in the 1720s.

Production and reactions

Potassium sulfite is produced by the thermal decomposition of

potassium metabisulfite Potassium metabisulfite, K2S2O5, also known as potassium pyrosulfite, is a white crystalline powder with a pungent odour. It is mainly used as an antioxidant or chemical sterilant. As a disulfite, it is chemically very similar to sodium metabi ...

at 190 °C: :

Structure

The structure of solid , as assessed by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

. The S-O distances are 1.515 Å, and the O-S-O angles are 105.2°

References

{{Sulfites Potassium compounds Sulfites