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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 ...
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:
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]
12.69 is the conversion factor from mEq sodium thiosulfate to grams of iodine (the molecular weight of iodine is 126.9 g/mol); W is the weight of the sample in grams. The determination of IV according to Wijs is the official method currently accepted by international standards such as DIN 53241-1:1995-05, AOCS Method Cd 1-25, EN 14111 and ISO ...
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 ...
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 reacted with ethylenediaminetetraacetic acid to give a pink color. [ 2 ]
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 ...
This elementary reaction consumes exactly one molar equivalent of water vs. iodine. Iodine is added to the solution until it is present in excess, marking the end point of the titration, which can be detected by potentiometry. The reaction is run in an alcohol solution containing a base, which consumes the sulfur trioxide and hydroiodic acid ...