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This clock reaction uses sodium, potassium or ammonium persulfate to oxidize iodide ions to iodine. Sodium thiosulfate is used to reduce iodine back to iodide before the iodine can complex with the starch to form the characteristic blue-black color. Iodine is generated: 2 I − + S 2 O 2− 8 → I 2 + 2 SO 2− 4. And is then removed:
The relevant reaction is akin to the iodine reaction: thiosulfate reduces the hypochlorite (the active ingredient in bleach) and in so doing becomes oxidized to sulfate. The complete reaction is: 4 NaClO + Na 2 S 2 O 3 + 2 NaOH → 4 NaCl + 2 Na 2 SO 4 + H 2 O. Similarly, sodium thiosulfate reacts with bromine, removing the free bromine from ...
The iodine content and thus the active chlorine content can be determined with iodometry. [ 3 ] The determination of arsenic(V) compounds is the reverse of the standardization of iodine solution with sodium arsenite , where a known and excess amount of iodide is added to the sample:
Percent active chlorine values have now virtually replaced the older system of chlorometric degrees: 1% active chlorine is equivalent to 3.16 °Cl. Taking the (reasonable) assumption that all active chlorine present in a liquid bleach is in the form of hypochlorite ions, 1% active chlorine is equivalent to 0.141 mol/kg ClO − (0.141 mol/L if ...
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 reduction reaction is analogous to the iodine reduction reaction. Treatment of tapwater requires between 0.1 and 0.3 grams of pentahydrated (crystalline) sodium thiosulfate per 10 L of water [citation needed]. Many animals are sensitive to chloramine, and it must be removed from water given to many animals in zoos. [citation needed]
Iodine monochloride and iodine monobromide may be prepared simply by reacting iodine with chlorine or bromine at room temperature and purified by fractional crystallisation. Both are quite reactive and attack even platinum and gold, though not boron, carbon, cadmium, lead, zirconium, niobium, molybdenum, and tungsten. Their reaction with ...
These iodine compounds are hypervalent because the iodine atom formally contains in its valence shell more than the 8 electrons required for the octet rule. Hypervalent iodine oxyanions are known for oxidation states +1, +3, +5, and +7; organic analogues of these moieties are known for each oxidation state except +7.