When rubidium persulphate reacts with somewhat more than twice the molecular proportion of strontium thiosulphate in solution, rubidium tetrathionate is formed:
Rb2S2O8+2SrS2O3 =Rb2S4O6+2SrSO4.
The strontium sulphite produced by decomposition of the excess of strontium thiosulphate then reacts with the rubidium tetrathionate, forming trithionate:
Rb2S4O6+SrS3 = Rb2S3O6+SrS2O3.
In presence of sulphurous acid a similar reaction takes place. The trithionate forms rhombic crystals isomorphous with those of the corresponding potassium salt, the density being 2.845. |