Sodium Sulphite

WHAT IS SODIUM SULPHITE

Sodium Sulphite (Na₂SO₃) is an inorganic compound with generally powder form. It is a water-soluble sodium salt. It is an ionic compound with reducing properties. Many companies manufacture it in tablet form. It is slightly alkaline in nature as a saturated solution of Sodium Sulphite is basic with a pH greater than 7(approx.=9). It is colorless solid.

Physical Properties

Its appearance is white hexagonal crystals. As described in the qualitative test, Sodium Sulphite responds to almost all tests for sodium salt. It occurs in anhydrous and heptahydrate forms. It is an odorless salt with a sulfurous or saline taste. It is completely soluble in glycerol but slightly soluble in alcohol. It does not oxidize and is a stable ionic compound.

Uses of Sodium Sulphite

• It serves as a bleaching agent.
• It is used in the preservation of food and beverages, industrially.
• In pharmaceuticals, it works as a stabilizing agent.
• It is used in food packing.
• To prevent discoloration of dried fruit, Sodium Sulphite is used.
• This ionic compound is used for the desulphurization and dechlorination process.
• To produce thiosulphate, it is an important component.

 Preparation

It is prepared by reacting sodium carbonate with sulphuric acid.

Another method involves the reaction of sulphur dioxide and sodium carbonate. This method is preferred industrially.

Chemical Properties

• It is decomposed when heated and emits toxic fumes of sulphur oxide and sodium oxide.
• It is basic in nature.
• Its refractive index is 1.56.
• It is fairly stable under recommended conditions.
• It is not flammable solid.
• Its vapour pressure is negligible.
• It reacts with peroxides and epoxides etc.
• To form corrosive material, it reacts with hot acid or steam.
• It is soluble in alcohol and slightly soluble in ethanol.
• Its anhydrous structure is hexagonal but heptahydrate associate with monoclinic crystals.