Iodine-thiosulfate

The amount of hypochlorite ion present in bleach can be determined by an oxidation-reduction titration. In this experiment, an iodine-thiosulfate titration will be utilized. The iodide ion is oxidized to form iodine, I2. This iodine is then titrated with a solution of sodium thiosulfate of known concentration. Three steps are involved ... 

A platinum oxidation state of +2.30 was determined by iodine-thiosulfate titrations9 assuming a molecular weight of 662.44. The calculated Pt oxidation state, based on the chemical analyses and crystallographic analysis, is +2.38 0.02. °... 

Iodine-thiosulfate titrations were performed by Ms. E. Streets of Argonne National Laboratory. 

From a practical viewpoint the iodine-thiosulfate reaction is accurate under the usual experimental conditions, provided the pH is less than S. In alkaline solution (pH > 8) iodine reacts with hydroxyl ion to form hypoiodous acid (Kg 10 ),... 

Thiosulfate ion (8203 ) is a moderately strong reducing agent that has been widely used to determine oxidizing agents by an indirect procedure that involves iodine as an intermediate. With iodine, thiosulfate ion is oxidized quantitatively to tetrathion-ate ion (8405 ) according to the half-reaction... 

Thermogravimetric analyses indicate that the compound contains 1.8 mole water. The tentatively accepted platinum oxidation state is +2.27 based on the fluorine content of the compound and has an estimated standard deviation of 0.02. Iodine thiosulfate titrations indicate a platinum oxidation state of +2.26.8... 

After 2 hours of electrolysis10 at 1.5 V, the product, having filled the bottom of the beaker, is filtered in a plastic funnel. The crystals are then washed with two 6-mL portions of cold water and allowed to air dry. The yield of 1.4-1.5 g (3.2-3.4mmole) represents 88-94% based on original K2[Pt(CN)4] 3H20. Using X-ray diffraction powder patterns, it is established that the products of both syntheses given above are identical.8 The platinum oxidation state of 2.29(1) is established by iodine-thiosulfate titrations.8... 

Midwest Microlabs, Indianapolis, IN. This laboratory does not perform Pt or Cs analyses. When metal analyses are reported, they were performed by Galbraith Laboratory, Knoxville, TN. The presence of alkali metals, thallium, and platinum was confirmed by spectrographic analysis at Argonne National Laboratory. The authors wish to thank I. P. Faris and E. A. Huff for performing the spectrographic analyses, E. Street and K. Jensen for the iodine-thiosulfate titrations, and E. Sherry for the X-ray powder patterns. 

To 300 ml. of a vigorously boiling solution that is normal with respect to sodium carbonate and 0.4 N in sodium hydroxide (12,6 g. NaHCOj -b 10.8 g. NaOH), about 5 g. of dry europium(II) sulfate as prepared above is added gradually. Shortly after the addition, the mixture becomes dark in color but on continued boiling the dark color disappears, and a lemon-yeUow, dense, crystalline precipitate of europium(II) carbonatef forms. The euro-pium(II) carbonate is filtered and dried in air at 75°. Yield 90 per cent. Anal. Nearly 100 per cent (iodine-thiosulfate titration). 

Peroxide levels were determined by titration of a slurry of the particles with iodine-thiosulfate. 

One such scheme involved the termination of the "living" particle with oxygen to give the lithium salt of styryl hydroperoxide. This salt was converted to the hydroperoxide by neutralization with acetic acid or to the peracetate by reaction with acetyl chloride. The yield of hydroperoxide was determined by titration of a slurry of the particles with iodine-thiosulfate. Figure 15 shows that at low temperatures essentially all of the carbanions are converted to hydroperoxide. 

The iodine/thiosulfate reaction can be used only in a slightly acidic medium, that is, in the approximate range 2 < pH<5. In a strongly acidic medium (pH<2), thiosulfuric acid, which forms in these conditions, decomposes into sulfurous acid and sulfur according to the reactions... 

This may be the explanation of the fact that tri-iodide ions appear again about the equivalence point of the iodine/thiosulfate reaction. 

Iodine-Thiosulfate. The reaction between sodium thiosulfate and... 

Thermogravimetric analysis (25-100°) shows a <0.05% weight loss, indicating that Tl4(C03)[Pt(CN)4] is anhydrous. Emission spectrographic analysis indicates the product to be of high purity it contains the metals Tl and Pt and impurities as follows faint traces of Ca and Li (<0.001%). Iodine-thiosulfate titration studies are negative, indicating no partial oxidation of Pt therefore, Pt is present as Pt °. 

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