potassium iodate is an inorganic compound of iodine, specifically a salt, having the chemical formula KIO3 . Iodine, element of the group of halogens (F, Cl, Br, I, As), this salt has an oxidation number of +5; Because of this it is a strong oxidizing agent. KIO 3 dissociates in the aqueous medium to form the K ion + and IO . 3 – .
It is synthesized by reacting potassium hydroxide with iodic acid: HIO 3 (aq) + KOH (s) => KIO 3 (aq) + H 2 O (L) Also, it is molecular iodine with potassium hydroxide: 3 I can be synthesized by reacting 2 (s) + 6KOH (s) => KIO 3 (aq) + 5KI (aq) + 3H 2 O (L).
physical and chemical properties
It is an odorless white solid, with fine crystals and a type of crystalline structure. It has a density of 3.98 g/mL, a molecular weight of 214 g/mol and an absorption band in the infrared (IR) spectrum.
It has a melting point: 833 aK (560 C), which corresponds to strong ionic interactions between K ions. + and IO 3 – . At high temperatures, it undergoes a thermal decomposition reaction, releasing molecular oxygen and potassium iodide:
2KIO 3 (s) => 2KI (s) + 3O 2 (G)
It has solubilities in water that vary from 4.74 g/100mL to 0 C, to 32.3 g/100mL at 100mC producing a colorless aqueous solution. In addition, it is insoluble in alcohol and nitric acid, but soluble in dilute sulfuric acid.
Its affinity for water is not appreciable, which explains why it is not hygroscopic and does not exist as hydrated salts (KO 3 H 2 O).
oxidizing agent
Potassium iodate, as indicated by its chemical formula, contains three oxygen atoms. It is a strongly electronegative element and because of this property, it “exposes” an electronic reduction in the cloud surrounding the iine.
The contribution due to this reduction, be that as the oxidation number of iodine can be calculated as (, 1, +2, +3, +5, +7), is +5 in the case of this salt. .
what does this mean? Before that species capable of yielding its electrons, iodine will accept them in its ionic form (IO 3 – ) to become molecular iodine and has an oxidation number equal to 0.
After this clarification it can be determined that potassium iodate is an oxidizing compound that reacts strongly with reducing agents in many redox reactions; In all of these, one is known as the iodine clock.
The iodine clock consists of a redox process of slow and fast steps, in which the fast steps are marked by a KO solution 3 to which starch is added to sulfuric acid. Next, starch – once its structure is produced between species I and anchor 3 – will turn the solution from colorless to dark blue.
Io 3 – + 3 HSO 3 – → I – + 3 HSO 4 –
Io 3 – + 5 I – + 6 H + → 3 I 2 + 3 H 2 O
I 2 + HSO 3 – + H 2 O → 2 I – + HSO 4 – + 2H + (dark blue due to the starch effect)
chemical composition
The chemical structure of potassium iodate is illustrated in the upper image. IO ions 3 – are represented by the “tripod” of red and purple regions, while K ions + are represented by purple regions.
But what is the point of these tripods? The correct geometric shapes of these ions are actually trigonal pyramids, with oxygen forming a triangular base, and the non-shared pair of electrons in iodine moving up, occupying space and forcing the I-O link down and two. Link I = O.
This molecular geometry corresponds to a sp hybridization of the 3 central iodine atom; However, another approach shows that one of the oxygen atoms forming bonds with the “d” orbitals of iodine is actually a sp hybridization. 3d 2 (Iodine may have ” d ” orbitals that expand its valence shell).
Crystals of this salt can undergo a transition to the structural phase (an arrangement other than the monoclinic) as a result of the different physical conditions that are subject to them.
Uses and Applications of Potassium Iodate
medical use
Potassium iodate is commonly used to prevent the accumulation of radioactivity in the thyroid 131 I, when this isotope is used in the determination of iodine uptake by the thyroid as a component of thyroid gland functioning.
Similarly, potassium iodate is used as a topical antiseptic (0.5%) in mucosal infections.
use in industry
It is added to the feed of farm animals as a supplement to iodine. Therefore, potassium iodate is used in industry to improve the quality of flour.
analytical use
In analytical chemistry, thanks to its stability, it is used as the primary standard in the standardization of sodium thiosulfate standard solutions (Na 2 S 2 O 3 ), to determine the concentration of iodine in samples.
This means that the amount of iodine can be determined by volumetric techniques (titration). In this reaction, potassium iodate rapidly oxidizes to the iodide anion I – , by the following chemical equation:
Io 3 – + 5I – + 6H + => 3I 2 + 3H 2 O
Iodine, I 2 , is titrated with a solution of Na 2 S 2 O 3 for its standardization.
use in laser technology
Studies have confirmed the interesting piezoelectric, pyroelectric, electro-optical, ferroelectric properties and non-linear optics of KeO crystals 3 . It has great potential in the technology of lasers in the electronic field and for materials made with this compound.
Health Risks of Potassium Iodate
In high doses may cause irritation of the oral mucosa, skin, eyes and respiratory tract.
Toxicity experiments of potassium iodate in animals have allowed it to be observed that in fasting dogs, given orally, at doses of 0.2–0.25 g/kg body weight, the compound causes vomiting.
If these vomiting is avoided, it causes the animal’s condition to deteriorate, as it induces anorexia and prostration before death. Their autopsies allowed to observe necrotic lesions in the liver, kidneys and intestinal mucosa.
Because of its oxidizing power, it represents a fire risk when exposed to flammable materials.
