Potassium iodate

Crystal structure
__ K + __ I 5+ __ O 2−
Crystal system	triclinic
Space group	P 1 (No. 1)
Lattice parameters	a  = 8.923  Å , b  = 8.942 Å, c  = 7.709 Å, α  = 54.4 °, β  = 125.3 °, γ  = 90.6 °
General
Surname	Potassium iodate
other names	Potassium iodate Potassium iodate
Ratio formula	KIO 3
Brief description	white, crystalline solid
External identifiers / databases
CAS number 7758-05-6 EC number 231-831-9 ECHA InfoCard 100,028,938 PubChem 23665710 ChemSpider 22856 Wikidata Q414599
properties
Molar mass	214.00 g mol −1
Physical state	firmly
density	3.98 g cm −3
Melting point	560 ° C (decomposition)
solubility	moderate in water (92 g l −1 at 25 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 272-315-319-335 P: 220-261-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Potassium is the potassium - salt of iodic acid . The white, crystalline solid is fire-promoting and can be used as an oxidizing agent.

Potassium iodate

Manufacturing

Iodates can be obtained from iodine and hot alkali. This is how potassium iodate is made from iodine and hot potassium hydroxide :

${\displaystyle {\ce {6KOH + 3I2 -> 5KI + KIO3 + 3H2O}}}$

This reaction is analogous to the production of chlorates from chlorine and hot lye.

Properties and use

Potassium iodate forms colorless crystals that are only sparingly soluble in water. The solubility increases with increasing temperature.

Solubility of Potassium Iodate in Water
temperature	in ° C	0	10	20th	30th	40	60	80	100
concentration	in g / 100 g H 2 O	4.60	6.27	8.08	10.3	12.6	18.3	24.80	32.3

Iodates are extremely good oxidizing agents. When their solutions are acidified, they are in equilibrium with their acidity; the solution then has a strong oxidizing effect, the oxidation potential being +1.196 V. In acidic solution, iodates react with iodide to form iodine, so comproportioning takes place:

${\displaystyle {\ce {5I- + IO3- + 6H3O+ -> 3I2 + 9H2O}}}$

This reaction is a partial reaction of the Landolt reaction , in which a color change only takes place after a certain time and in which potassium iodate is preferably used.

Potassium iodate has a triclinic structure at room temperature . This has the space group P 1 (space group no. 1) with the lattice parameters a = 8.923 Å , b = 8.942 Å, c = 7.709 Å, α = 54.4 °, β = 125.3 °, γ = 90.6 °. At 72.5 ° C this changes into a monoclinic structure with the space group Cm (No. 8) , at 212 ° C into a trigonal structure with the space group R 3 m (No. 166) .

The most important applications of potassium iodate are in analytical chemistry, where it is also used as a primary titre .

Iodized table salt contains approx. 20 ppm potassium or sodium iodate (0.020 mg / g). Potassium iodide cannot be used for this because it can be oxidized too easily . Medical iodine deficiency tablets contain around the recommended daily requirement, around 0.1 mg / piece. Special radiation protection iodine tablets , on the other hand, are dosed 1000 times higher at around 100 mg / piece.

safety instructions

As strong oxidizing agents, iodates must be kept away from reducing agents such as sulfur , metal powders or organic substances. In animal experiments with rabbits, potassium iodate caused severe irritation to the eyes and skin.

Individual evidence

1. ↑ ^{a b c d} Data sheet potassium iodate (PDF) from Merck , accessed on August 15, 2010.
2. ↑ ^{a b} Entry on potassium iodate in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
3. ^ ^{A b} Dean, JA: Lange's Handbook of Chemistry, 15th Ed. 1999, McGraw-Hill, Inc. New York, ISBN 0-07-016384-7 .
4. ^ SA Hamid: Symmetry of KIO ₃ and the structure of the room temperature phase. In: Zeitschrift für Kristallographie, Kristallgeometrie, Kristallphysik, Kristallchemie , 137, 1973, pp. 412-421, doi: 10.1524 / zkri.1973.137.16.412 .
5. ↑ Entry on iodized table salt. In: Römpp Online . Georg Thieme Verlag, accessed on April 29, 2016.
6. ↑ Data sheet potassium iodate from AlfaAesar, accessed on August 15, 2010 ( PDF )(JavaScript required) .

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !