Polythionic acids
Polythionic acids are among the oxygen acids of sulfur with the general formula H 2 S 2 + n O 6 or HO 3 S – S n –SO 3 H (n = 1, 2, 3,… 11). Polythionic acids are relatively stable in aqueous solutions. The resistance decreases with increasing sulfur content. The stability of their salts increases in acidic solution from tri- to hexathionate and decreases again to octathionate. In an alkaline solution, the resistance of the polythionate decreases with increasing sulfur content.
presentation
By introducing hydrogen sulfide in a solution of sulfur dioxide ( sulfurous acid ) is a colorless and odorless solution "is obtained Wackenroder liquid", which mainly tetrathionic acid H 2 S 4 O 6 and pentathionic H 2 S 5 O 6 contains.
Meaning and use
The tetrathionate ion is created during iodometry .
Historical
Already John Dalton had stated that in mixtures of aqueous solutions of sulfur dioxide and hydrogen sulfide smell of both types of gas will disappear, probably makes a chemical reaction. He wrote: “If you mix water, which has been individually impregnated with each of these types of gas, until mutual saturation takes place, or until after shaking the odor of none of the types of gas is noticeable, you get a milky liquid, which you get can be kept for several weeks without noticeable change or tendency to precipitate. Their taste is bitter and slightly sour, and very different from a mere mixture of sulfur and water. If it is boiled, sulfur is deposited and sulfuric acid is found in the clear liquid. ” Heinrich Wilhelm Ferdinand Wackenroder examined the aqueous solutions together with his assistant Hermann Ludwig (1819–1873) and suggested“ a new acid des Sulfur “, the pentathionic acid. Thereafter, such solutions were called Wackenroder's liquid . The name caught on, although Hermann Ludwig tried to link his name to pentathionic acid.
literature
- Entry to polythionic acids. In: Römpp Online . Georg Thieme Verlag, accessed on June 20, 2014.
Individual evidence
- ^ John Dalton, Friedrich Wolff, A new system of the chemical part of natural science, Julius Eduard Hitzig, Berlin 1813, Volume 2, page 190, online at Google Books .
- ↑ H. Wackenroder, About a new acid of sulfur, Archive of Pharmacy Volume 97, No. 3 (1846) 272-288, doi : 10.1002 / ardp.18460970303 , online in the Internet Archive .
- ↑ H. Wackenroder, Determination of the Oxygen Content of Pentathionic Acid , Archiv der Pharmazie Volume 98, No. 2 (1846), 140–151, doi : 10.1002 / ardp.18460980203 , online at the Bayerische Staatsbibliothek .
- ^ Hermann Ludwig, Zur Geschichte der Pentathionäure, Archiv der Pharmazie, Volume 135, No. 1, Pages 9-13, 1856, doi : 10.1002 / ardp.18561350105 , online in the Internet Archive .