Oxidizing agents titration

A common laboratory technique for determining the concentration of a solute is titration (Fig. L.2). Titrations are usually either acid-base titrations, in which an acid reacts with a base, or redox titrations, in which the reaction is between a reducing agent and an oxidizing agent. Titrations are widely used to monitor water purity and blood composition and for quality control in the food industry. 

The quantitative conversion of thiosulfate to tetrathionate is unique with iodine. Other oxidant agents tend to carry the oxidation further to sulfate ion or to a mixture of tetrathionate and sulfate ions. Thiosulfate titration of iodine is best performed in neutral or slightly acidic solutions. If strongly acidic solutions must be titrated, air oxidation of the excess of iodide must be prevented by blanketing the solution with an inert gas, such as carbon dioxide or... 

Ferrous Sulfdte Titration. For deterrnination of nitric acid in mixed acid or for nitrates that are free from interferences, ferrous sulfate titration, the nitrometer method, and Devarda s method give excellent results. The deterrnination of nitric acid and nitrates in mixed acid is based on the oxidation of ferrous sulfate [7720-78-7] by nitric acid and may be subject to interference by other materials that reduce nitric acid or oxidize ferrous sulfate. Small amounts of sodium chloride, potassium bromide, or potassium iodide may be tolerated without serious interference, as can nitrous acid up to 50% of the total amount of nitric acid present. Strong oxidizing agents, eg, chlorates, iodates, and bromates, interfere by oxidizing the standardized ferrous sulfate. 

Conductometric titration rests on the marked changes that occur near the titration endpoint in the relation between conductivity and the amount of titrant added (an extreme or inflection point). It is used in particular for the titration of acids with base (and vice versa) in colored and turbid solutions or solutions containing reducing and oxidizing agents (i.e., in those cases where the usual color change of acid-base indicators cannot be seen). 

Theory Iodine in aqueous solution acts as an oxidizing agent which forms the basis of assay methods involving direct titration with iodine. Thus, we have ... 

As it has been discussed earlier, iodine cannot be used directly as an oxidizing agent in such type of assays, whereas the liberated iodine quantitatively produced by the oxidation of iodide with bromine (excess) may be assayed by titrating against sodium thiosulphate solution. 

Potassium iodate is a fairly strong oxidizing agent that may be used in the assay of a number of pharmaceutical substances, for instance benzalkonium chloride, cetrimide, hydralazine hydrochloride, potassium iodide, phenylhydrazine hydrochloride, semicarbazide hydrochloride and the like. Under appropriate experimental parameters the iodate reacts quantitatively with both iodides and iodine. It is, however, interesting to observe here that the iodate titrations may be carried out effectively in the presence of saturated organic acids, alcohol and a host of other organic substances. 

Titrate 300 mL 0.1 M FeQ2 solution to pH 8 with 5 M NaOH with stirring. Add 40 mL 30% H2O2 in one lot. As the reaction is violent, it should be carried out in a 2 L beaker in a fume hood. Upon addition of the oxidizing agent, the green suspension rapidly turns reddish brown. Centrifuge, wash and dry the product at 40 °C. 

Elemental composition H 5.44%, N 18.90%, 0 32.39%, S 43.27%. It is dissolved in water and the aqueous solution may be analyzed for thiosulfate by titrating against a standard solution of an oxidizing agent, such as potassium dichromate or potassium permanganate. Ammonium ion in the aqueous solution may be determined by colorimetry, titrimetry, or ion-specific electrode method (see Ammonia). 

Elemental composition H 4.92%, N 17.06%, O 58.49%, S 19.59%. The concentration of hydroxylamine sulfate in aqueous solution may be measured by coulometric titration against a standard solution of oxidizing agent, such as bromine (See Hydroxylamine). Sulfate anion may be measured by ion chromatography. 

Aqueous solutions of iodic acid serve as strong oxidizing agents. The acid also is used in redox titrations. 

Potassium iodate is an oxiding agent in volumetric analysis. It releases iodine in KIO3-KI solutions for iodometric titrations. It also is a topical antiseptic and an additive to food to provide nutrient iodine. 

Vanadyl sulfate may be analyzed by titration with a standard solution of potassium permanganate (See Vanadium Pentoxide, Analysis) or any suitable oxidizing agent. An aqueous solution may be analyzed for vanadium by AA or ICP (See Vanadium). 

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