Ammonium sulfite is the ammonium

Ammonium

The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...

 salt of sulfurous acid

Sulfurous acid

Sulfurous acid is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid exists in solution, but the molecule has been detected in the gas phase...

 with the chemical formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 (NH₄)₂SO₃.

Preparation

Ammonium sulfite can be prepared by the reaction of ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 with sulfur dioxide

Sulfur dioxide

Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...

 in aqueous solution

Aqueous solution

An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending aq to the relevant formula, such as NaCl. The word aqueous means pertaining to, related to, similar to, or dissolved in water...

:

2NH₃ + SO₂ + H₂O → (NH₄)₂SO₃

Uses

For cosmetics, ammonium sulfite is used as a hair straightening agent and a hair waving agent. Ammonium based hair products have been made to replace sodium hydroxide based products due to the destructive nature of sodium hydroxide on hair.

The most common food product with ammonium sulfite is caramel coloring. According to the FDA, caramel coloring contains ammonium, potassium, or sodium sulfite.

Ammonium sulfite is used as a reducing agent in photography. When film photographs are being developed ammonium sulfite can be one of the reducing agents used to develop the negative. .

Ammonium sulfite can also be used in the making of bricks. The bricks made using ammonium sulfite are mainly used for blast furnace linings.

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.

Ammonium sulfite has been used in gas scrubbers. The ammonium sulfite reacts with acidic air samples as a reducing agent. The Air is reduced to a more neutral pH which makes it less harmful to the environment.

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.

Hazards

Ammonium sulfite can be dangerous to handle. Ammonium sulfite has a toxic effect on humans. It is very hazardous in case of ingestion, it has a sulfurous taste. Ammonium sulfite is also hazardous in case of skin contact and it will irritate any skin that comes into contact with. Inhalation is another route of entry for ammonium sulfite to enter in a dangerous manner. Ammonium suifite is also hazardous when it comes into contact with eyes. The LD₅₀ has not been determined.