Iodate Ion
Definition and meaning of Iodate Ion in chemistry.
Iodate ion is the polyatomic anion IO3-, in which a central iodine atom in the +5 oxidation state is bonded to three oxygen atoms. It is the conjugate base of iodic acid (HIO3) and forms salts such as potassium iodate (KIO3).
In more detail
Like the analogous chlorate and bromate ions, iodate has a trigonal pyramidal shape because a lone pair on iodine occupies one corner of an otherwise tetrahedral electron arrangement. Iodate is a moderately strong oxidizing agent, especially in acidic solution, where it oxidizes iodide ion to iodine (I2). This reaction is the basis of iodometric titrations and the classic iodine clock reaction. Potassium iodate is also used as a primary standard in analytical chemistry and as an iodine source in iodized table salt.
Key facts
| Formula | IO3- |
|---|---|
| Oxidation state of iodine | +5 |
| Molecular geometry | Trigonal pyramidal |
| Field | Inorganic Chemistry |
In an iodine clock reaction, potassium iodate (KIO3) is mixed with sodium hydrogen sulfite and starch; iodate is first reduced to iodide, which is then oxidized by remaining iodate to iodine, producing a sudden blue-black starch-iodine color once the sulfite is consumed.
Frequently asked questions
What is the charge on the iodate ion?
Iodate carries a single negative charge (IO3-), balanced by one cation such as K+ in potassium iodate.
How does iodate react with iodide?
In acidic solution, iodate oxidizes iodide to iodine while iodate itself is reduced, a reaction used in iodometric titrations to quantify oxidizing or reducing agents.