In the context of sodium thiosulfate, the prefix "hypo-" indicates the presence of a thiosulfate ion (S2O3^2-). Sodium thiosulfate is also known by its chemical formula Na2S2O3, and it is commonly referred to as "hypo."
The term "hypo" has historical origins and was derived from "hyposulfite," which was used to describe compounds containing the thiosulfate ion. Over time, "hyposulfite" was shortened to "hypo."
Sodium thiosulfate, or hypo, is widely used for various purposes, including as a dechlorinating agent in water treatment. It is effective in neutralizing chlorine and chloramine, which are commonly added to tap water for disinfection purposes. Sodium thiosulfate reacts with chlorine and converts it into chloride ions, thereby removing the chlorine from the water.
The dechlorination process involving sodium thiosulfate is commonly used in aquariums, fish tanks, and when treating water for sensitive aquatic organisms, as chlorine can be harmful to them. Sodium thiosulfate effectively removes chlorine without introducing any harmful byproducts.
So, in summary, "hypo" in sodium thiosulfate refers to the compound's association with the thiosulfate ion (S2O3^2-), and it is indeed the same substance used for dechlorinating water.