Sodium sulfite 98+%, pure

What is Sodium Sulfite?

Sodium sulfite Na2SO3 (not to be confused with sodium sulfide Na2S) is the sodium salt of sulfuric acid.

Sodium sulfite is a white to slightly yellowish, odorless, crystalline powder. It crystallizes as a heptahydrate from an aqueous solution. It is hygroscopic and can be oxidized to sodium sulfate (Na2SO4) by oxygen. It decomposes with acids to form sulfur dioxide. The water of crystallization of the heptahydrate disappears from 150 °C. The anhydrous form is more stable against oxidation than the heptahydrate. Sodium sulfite is easily soluble in water, the solution has an alkaline reaction and has a reducing effect. It has a germicidal effect.

The compound has a trigonal crystal structure with space group P3 (space group no. 147).

What is Sodium Sulfite used for?

Sodium sulfite serves as a preservative and antioxidant for food (additive number E221). As part of the so-called dumpling aid, it prevents potato dough from browning (oxidizing). Please note that this particular sodium sulfite is not food grade. In the photo industry, anhydrous sodium sulfite photo grade is used as an antioxidant for developer solutions. In the chemical and chemical-technical industry, sodium thiosulfate (fixing salt) is produced from sodium sulfite with the addition of sulfur. In the chemical fiber and textile industry it is used as a bleaching agent and to destroy active chlorine. It is also an aid to water treatment as it acts as a corrosion protection by removing oxygen and is used to remove chlorine from tap water. In the rubber and pulp industry, it helps to improve the quality of products. It is also an intermediate in the production of sodium dithionite.
It is offered as an active ingredient against the formation of germs or algae.
It is an antidote for nicotine poisoning. In addition to sodium dithionite, it is used as an active ingredient in the ink killer and is a component of stain removers.

Technical data

Empirical formula Na2SO3
Molar mass (M) 126,04 g/mol
Density (D) 2,63 g/cm³
Melting point (mp) 911 °C
WGK 1
CAS No. 7757-83-7
EG-Nr. 231-821-4

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