Ammonium sulfite is the

ammonium Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) polyatomic ion, molecular ion with the chemical formula or . It is formed by the protonation, addition of a proton (a hydrogen nucleu ...

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 ...

sulfurous acid Sulfuric(IV) acid (United Kingdom spelling: sulphuric(IV) acid), also known as sulfurous (UK: sulphurous) acid and thionic acid, is the chemical compound with the chemical formula, formula . Raman spectroscopy, Raman spectra of solutions o ...

with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

(NH₄)₂SO₃.

Preparation

Ammonium sulfite can be prepared by the reaction of

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

with

sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...

aqueous solution An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, also known as sodium chloride (NaCl), in water ...

: : Ammonium sulfite is produced in gas scrubbers, now obsolete, consisting of ammonium hydroxide to remove sulfur dioxide from emissions from power plants. The conversion is the basis of the Walther Process. The resulting ammonium sulfite can be air oxidized to give

ammonium sulfate Ammonium sulfate (American English and international scientific usage; ammonium sulphate in British English); (NH4)2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen a ...

Uses

Ammonium sulfite is the precursor to

ammonium thiosulfate Ammonium thiosulfate (ammonium thiosulphate in British English) is an inorganic compound with the formula . It is white crystalline solid with ammonia odor, readily soluble in water, slightly soluble in acetone and insoluble in ethanol and diethy ...

, by reaction with elemental sulfur.

Niche

For cosmetics, ammonium sulfite is used as a hair straightening agent and a hair waving agent.Europe. European Commission. Health and Consumers. Cosmetics
- CosIng osmetics Directive (v.1) European Commission. Web. 26 Oct. 2011. Ammonium based hair products have been made to replace

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

-based products due to the destructive nature of sodium hydroxide on hair. The most common food product with ammonium sulfite is caramel coloring E150d. According to the FDA, caramel coloring contains ammonium, potassium, or sodium sulfite.United States. FDA. CFR - Code of Federal Regulations Title 21. Health and Human Services. 1 Apr. 2011. Web
/ref> Ammonium sulfite is used as a preservative for fixers in photography. When film photographs are being developed ammonium sulfite can be one of the reducing agents used to preserve the hypo (

sodium thiosulfate Sodium thiosulfate (sodium thiosulphate) is an inorganic compound with the formula . Typically it is available as the white or colorless pentahydrate (x = 5), which is a white solid that dissolves well in water. The compound is a reducing agent an ...

or ammonium thiosulfate). Ammonium sulfite can also be used in the making of bricks. The bricks made using ammonium sulfite are mainly used for blast furnace linings.O'Neil, Maryadele J. ''The Merck Index: an Encyclopedia of Chemicals, Drugs, and Biologicals''. Whitehouse Station, NJ: Merck, 2001. 561. Print. Ammonium sulfite can be included in lubricants for cold metal working. The lubricants are intended to reduce friction to keep heat production down and keep impurities out of the metals.

Chemical properties

Ammonium sulfite is a reducing agent. It emits sulfur dioxide and oxides of nitrogen upon heating to decomposition. The specific gravity of ammonium sulfite is 1.41. The refractive index of ammonium sulfite is 1.515.

References

{{Sulfites Ammonium compounds Sulfites