Overview

Sodium thiosulfate (SO-dee-um THYE-oh-SUL-fate) is a colorless to white crystalline solid or powder with no odor and a cooling, bitter taste. The compound usually occurs in the form of the pentahydrate (Na₂S₂O₃·5H₂O). Sodium thiosulfate is an antichlor, a compound that reacts with and neutralizes excess chlorine used in some industrial, commercial, or other applications. Two other popular antichlors are sodium bisulfite (NaHSO₃) and sodium sulfite (Na₂SO₃). Some of the most important applications of antichlors are in the production of pulp and paper and in the textile industry. After pulp, paper, or a textile has been treated with chlorine to bleach the material, an antichlor such as sodium thiosulfate is added to remove any remaining chlorine from the reaction vat. The antichlor itself is then removed by washing with water.

Key Facts

Other Names:

Sodium hyposulfite; thiosulfic acid sodium salt

Formula: