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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]
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]
The bisulfite ion (IUPAC-recommended nomenclature: hydrogensulfite) is the ion HSO − 3. Salts containing the HSO − 3 ion are also known as "sulfite lyes". [1] Sodium bisulfite is used interchangeably with sodium metabisulfite (Na 2 S 2 O 5). Sodium metabisulfite dissolves in water to give a solution of Na + HSO − 3. Na 2 S 2 O 5 + H 2 O ...
Therefore, silver halide crystal size is proportional to film speed. The metallic silver image has dark (black) appearance. Once the desired level of reduction is achieved the development process is halted by washing in a dilute acid and then the undeveloped silver halide is removed by dissolving it in a thiosulfate solution, a process called ...
Sodium bisulfite (or sodium bisulphite, sodium hydrogen sulfite) is a chemical mixture with the approximate chemical formula NaHSO 3. Sodium bisulfite is not a real compound, [ 2 ] but a mixture of salts that dissolve in water to give solutions composed of sodium and bisulfite ions.
Sodium bisulfate, also known as sodium hydrogen sulfate, [a] is the sodium salt of the bisulfate anion, with the molecular formula NaHSO 4.Sodium bisulfate is an acid salt formed by partial neutralization of sulfuric acid by an equivalent of sodium base, typically in the form of either sodium hydroxide (lye) or sodium chloride (table salt).
Sodium tetrathionate is formed by the oxidation of sodium thiosulfate (Na 2 S 2 O 3), e.g. by the action of iodine: [1] 2 Na 2 S 2 O 3 + I 2 → Na 2 S 4 O 6 + 2 NaI. The reaction is signaled by the decoloration of iodine. This reaction is the basis of iodometric titrations. Other methods include the coupling of sodium bisulfite with disulfur ...
Historically, mercurous sulfate has been used to catalyze the reaction. [3] Chlorosulfuric acid is also an effective agent: C 6 H 6 + HSO 3 Cl → C 6 H 5 SO 3 H + HCl. In contrast to aromatic nitration and most other electrophilic aromatic substitutions this reaction is reversible. Sulfonation takes place in concentrated acidic conditions and ...