Sodium thiosulfate is used as a component in hand warmers and other chemical heating pads that produce heat by exothermic crystallization of a super cooled solution.
Hypo is used in Bleach.
In pH testing of bleach substances.
To de-chlorinate tap water for aquariums or treat effluent from waste water treatments prior to release into rivers. The amount of Sodium thiosulphate required can vary with the pH of the water. A range of approximately 2 to 7 parts sodium thiosulfate to neutralize one part chlorine is generally suggested. To neutralize 1 liter of a 200 ppm chlorine solution, approximately - grams of sodium thiosulfate would be required.
It is used to lower chlorine levels in swimming pools and spas following super chlorination.
It is used to remove iodine stains, . after the explosion of nitrogen triiodide.
It is used in bacteriological water assessment.
It is used in the tanning of leather.
Melted sodium thiosulfate is very easy to overcool to room temperature and when crystallization is forced, the sudden temperature jump to can be experienced by touch. It is used in phase change material.
Sodium thiosulfate is used in paper industry.
It is used in medicine and as disinfectant. A low amount can be found in natural hot springs water, but they do have trace sodium sulfide too, which is why it can used to treat skin problems and some bathe in it to relieve them of skin problems, rheumatism, although indirectly. It is systemically for cyanide or arsenic poisoning and topically as an antifungal.
It is used in electroplating.
As part of patina recipes for copper alloys.
Often used in pharmaceutical preparations as an anionic surfactant to aid in dispersion.