Sodium trithionate, Na₂S₃O₆

The Sodium trithionate can be prepared from sodium thiosulphate by oxidation with hydrogen peroxide, or by electrolysis in acid or alkaline solution. It is also formed by heating a solution of sodium mercuric thiosulphate:

Na₂Hg(S₂O₃)₂=Na₂S₃O₆+HgS.

The trihydrate can be prepared by the interaction of sulphur dioxide and sodium thiosulphate.

Sodium trithionate forms transparent plates, very soluble in water. The heat of formation in aqueous solution from the elements is given by Berthelot as 393.6 Cal. The heat of solution of the trihydrate is -10.1 Cal.