Formula (NH4)2SO3 Melting point 65 °C | Molar mass 116.15 g/mol | |
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Appearance colourless; hygroscopic Crystals | ||
Preparation properties of ammonium sulfite
Ammonium sulfite is the ammonium salt of sulfurous acid with the chemical formula (NH4)2SO3.
Contents
Preparation
Ammonium sulfite can be prepared by the reaction of ammonia with sulfur dioxide in aqueous solution:
2NH3 + SO2 + H2O → (NH4)2SO3Uses
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 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 or Ammonium Thiosulfate). Examples are given in Modern Photographic Processing, Volume I by Doctor Grant M. Haist of Eastman Kodak.
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.