Chemical Properties
white crystals or powder
Physical properties
Colorless crystals or white powder; monoclinic structure; density 3.90 g/cm3; stable at ordinary temperatures; melts at 560°C with partial decompo-sition, releasing oxygen; moderately soluble in cold water; 4.74 g/100mL at 0°C; greater solubility in boiling water 32.3 g/100mL at 100°C; soluble in potassium iodide solution; insoluble in alcohol and liquid ammonia.
Application
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.
The oxidation-reduction methods with potassium iodate invariably based on the formation of iodine monochloride (ICl) in a medium of strong hydrochloric acid solution.
Definition
A
white solid formed either by adding iodine
to a hot concentrated solution of potassium
hydroxide or by the electrolysis of
potassium iodide solution. No hydrates are
known. It is a source of iodide and iodic
acid. When treated with a dilute acid and a
reducing agent, the iodate ions are reduced
to iodine.
Definition
potassium iodate: A white crystallinesolid, KIO3, soluble in waterand insoluble in ethanol; monoclinic;r.d. 3.9; m.p. 560°C. It may be preparedby the reaction of iodine withhot concentrated potassium hydroxideor by careful electrolysis ofpotassium iodide solution. It is anoxidizing agent and is used as ananalytical reagent. Some potassiumiodate is used as a food additive.
Preparation
Potassium iodate can be produced by fusing potassium iodide with potassium chlorate, bromate or perchlorate:
KI + KClO3→KIO3+ KCl
The melt is extracted with water and potassium iodate is isolated from solution by crystallization.
Production Methods
Potassium iodate is formed (1) by electrolysis of potassium iodide under proper conditions, (2) by reaction of iodine and potassium hydroxide solution, and the fractional crystallization of iodate from iodide. Used as a source of iodate and iodic acid.
General Description
KIO3 can be used as a substitute of KI in radiation protection. A kinetic study of thermal degradation of KIO3 by γ-rays suggests that rate of decomposition increases while activation energy decreases upon irradiation.
Flammability and Explosibility
Nonflammable
Food additive
Iodine can be added to salt in the form of potassium iodide (KI) or potassium iodate (KIO3). Because KIO3 has higher stability in the presence of salt impurities, humidity, and porous packaging, it is the recommended form.
Potassium iodate, which is formed as a secondary product, is reduced by activated carbon. The product is purified by crystallization from water. Alternatively, iron (II) iodide, prepared by using iron powder and iodine, can be treated with potassium carbonate to obtain potassium iodide. High-purity potassium iodide can be prepared by the reaction of a potassium bicarbonate with hydriodic acid.
Overdosage
Overdose of potassium iodate, an iodized salt used for iodine supplementation in areas endemic for goiter, has been shown to cause profound visual loss and extensive retinal pigmentary abnormalities.78 FA reveals RPE window defects and ERG and VEP testing show marked impairment of retinal function. Visual acuity may improve slowly over several months.
Purification Methods
It has been crystallised twice from distilled water (3mL/g) between 100o and 0o, dried for 2hours at 140o and cooled in a desiccator. Analytical reagent grade material dried in this way is suitable for use as an analytical standard.
