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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:
Thiosulfate reacts with iodine to give tetrathionate, in this case potassium thiosulfate reacts with iodine to produce potassium tetrathionate and potassium iodide: 2 K 2 S 2 O 3 + I 2 → K 2 S 4 O 6 + 2 KI. Thiosulfate extensively forms diverse complexes with transition metals. In the era of silver-based photography, thiosulfate was consumed ...
Note that iodometry involves indirect titration of iodine liberated by reaction with the analyte, whereas iodimetry involves direct titration using iodine as the titrant. Redox titration using sodium thiosulphate, Na 2 S 2 O 3 (usually) as a reducing agent is known as iodometric titration since it is used specifically to titrate iodine. The ...
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 cut surface of an apple stained with iodine, indicating a starch level of 4–5. The iodine–starch test is a chemical reaction that is used to test for the presence of starch or for iodine. The combination of starch and iodine is intensely blue-black. [1] [2] The interaction between starch and the triiodide anion (I − 3) is the basis ...
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.
(B – S) is the difference between the volumes, in mL, of sodium thiosulfate required for the blank and for the sample, respectively; N is the normality of sodium thiosulfate solution in Eq/ L; 12.69 is the conversion factor from mEq sodium thiosulfate to grams of iodine (the molecular weight of iodine is 126.9 g/mol);
The brown precipitate then converts the iodide ion (I −) to iodine. The amount of dissolved oxygen is directly proportional to the titration of iodine with a thiosulfate solution. [ 1 ] Today, the method is effectively used as its colorimetric modification, where the trivalent manganese produced on acidifying the brown suspension is directly ...