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Sodium thiosulfate (sodium thiosulphate) is an inorganic compound with the formula Na 2 S 2 O 3 ·(H 2 O) x. Typically it is available as the white or colorless pentahydrate (x = 5), which is a white solid that dissolves well in water. The compound is a reducing agent and a ligand, and these properties underpin its applications. [2]
Pages in category "Light-sensitive chemicals" The following 13 pages are in this category, out of 13 total. This list may not reflect recent changes. A.
Thiosulfate (IUPAC-recommended spelling; sometimes thiosulphate in British English) is an oxyanion of sulfur with the chemical formula S 2 O 2− 3.Thiosulfate also refers to the compounds containing this anion, which are the salts of thiosulfuric acid, such as sodium thiosulfate Na 2 S 2 O 3 and ammonium thiosulfate (NH 4) 2 S 2 O 3.
The agent used is sodium thiosulfate, and reacts according to the following equation: [2] AgX(s) + 2 Na 2 S 2 O 3 (aq) → Na 3 [Ag(S 2 O 3) 2](aq) + NaX(aq) An indefinite number of positive prints can be generated from the negative by passing light through it and undertaking the same steps outlined above. [2]
Fixation is commonly achieved by treating the film or paper with a solution of thiosulfate salt. Popular salts are sodium thiosulfate—commonly called hypo—and ammonium thiosulfate—commonly used in modern rapid fixer formulae. [1] Fixation by thiosulfate involves these chemical reactions (X = halide, typically Br −): [2]
The fixer, typically sodium thiosulfate, is able to remove the unexposed silver halide by forming a water-soluble complex with it. And finally, a water wash sometimes preceded by a washing aid removes the fixer from the print, leaving an image composed of silver particles held in the clear gelatin image layer.
After development, the light sensitivity of the plate was arrested by removing the unexposed silver halide with a mild solution of sodium thiosulfate; Daguerre's initial method was to use a hot saturated solution of common salt. Gilding, also called gold toning, was an addition to Daguerre's process introduced by Hippolyte Fizeau in 1840. It ...
In 1839, washing with a solution of sodium thiosulfate ("hypo") was found to be the most effective way to make the results truly light-fast. The salt print process is often confused with Talbot's slightly later 1841 calotype or "talbotype" process, in part because salt printing was mostly used for making prints from calotype paper negatives ...