Sodium thiosulfate (Na2S2O3), also spelled sodium thiosulphate, is a colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3· 5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposulfite or "hypo".

Monoclinic crystal, melting point: 40-45ºC, relative density: 1.729 (17ºC).

The thiosulfate anion is tetrahedral in shape and is notionally derived by replacing one of the oxygen atoms by a sulfur atom in a sulfate anion. The S-S distance indicates a single bond, implying that the sulfur bears significant negative charge and the S-O interactions have more double bond character. The first protonation of thiosulfate occurs at sulfur.

Usage:

It is the fixing agent of photograph, antichlor and printing auxiliary of textile, printing and dyeing industry, and also used in manufacturing of synthetical dye, insecticides, synthetic fabrics. Moreover it is still used in medicine, leather, paper making and mineral concentration industries, etc.

Storage and handing :

Store the product in a cool and dry place, prevent from direct sunlight, water and moisture, avoid contact with strong add oxidants,Do not stores it for long time.