An iodate is the
polyatomic anion
A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zero. The term molecule may or may no ...
with the formula . It is the most common form of
iodine
Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...
in nature, as it comprises the major iodine-containing ores.
Iodate
salts
In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively c ...
are often colorless. They are the salts of
iodic acid
Iodic acid is a white water-soluble solid with the chemical formula . Its robustness contrasts with the instability of chloric acid and bromic acid. Iodic acid features iodine in the oxidation state +5 and is one of the most stable oxo-acids of ...
.
Structure
Iodate is pyramidal in structure. The O–I–O angles range from 97° to 105°, somewhat smaller than the O–Cl–O angles in chlorate.
Reactions
Redox
Iodate is one of several
oxyanion An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determine ...
s of iodine, and has an
oxidation number
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...
of +5. It participates in several redox reactions, such as the
iodine clock reaction
The iodine clock reaction is a classical chemical clock demonstration experiment to display chemical kinetics in action; it was discovered by Hans Heinrich Landolt in 1886. The iodine clock reaction exists in several variations, which each invol ...
. Iodate show no tendency to disproportionate to periodate and iodide, in contrast to the situation for chlorate.
Iodate is
reduced by
sulfite:
[
:6HSO3- + 2IO3- -> 2I- + 6HSO4-
Iodate oxidizes ]iodide
An iodide ion is the ion I−. Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine defic ...
:
:5I- + IO3- + 3H2SO4 -> 3I2 + 3H2O + 3SO4^2-
Similarly, chlorate oxidizes iodide to iodate:
:I- + ClO3- -> Cl- + IO3-
Iodate is also obtained by reducing a periodate
Periodate is an anion composed of iodine and oxygen. It is one of a number of oxyanions of iodine and is the highest in the series, with iodine existing in oxidation state +7. Unlike other perhalogenates, such as perchlorate, it can exist in two ...
with a sulfide
Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...
. The byproduct of the reaction is a sulfoxide
In organic chemistry, a sulfoxide, also called a sulphoxide, is an organosulfur compound containing a sulfinyl () functional group attached to two carbon atoms. It is a polar functional group. Sulfoxides are oxidized derivatives of sulfides. E ...
.
Acid-base
Iodate is unusual in that it forms a strong hydrogen bond with its parent acid:[
: IO3- + HIO3 -> H(IO3)2-
The anion is referred to as biiodate.
]
Principal compounds
* Calcium iodate
Calcium iodate is any of two inorganic compounds with the formula Ca(IO3)2(H2O)x, where x = 0 or 1. Both are colourless salts that occur as the minerals lautarite and bruggenite, respectively. A third mineral form of calcium iodate is dietzeite, ...
, Ca(IO3)2, is the principal ore of iodine. It is also used as a nutritional supplement for cattle.
* Potassium iodate
Potassium iodate ( K I O3) is an ionic chemical compound consisting of K+ ions and IO3− ions in a 1:1 ratio.
Preparation and properties
Potassium iodate is an oxidizing agent and as such it can cause fires if in contact with combustible materi ...
, KIO3, like potassium iodide
Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are u ...
, has been issued as a prophylaxis
Preventive healthcare, or prophylaxis, consists of measures taken for the purposes of disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental hea ...
against radioiodine
There are 37 known isotopes of iodine (53I) from 108I to 144I; all undergo radioactive decay except 127I, which is stable. Iodine is thus a monoisotopic element.
Its longest-lived radioactive isotope, 129I, has a half-life of 15.7 million year ...
absorption in some countries.
* Potassium hydrogen iodate (or potassium biiodate), KH(IO3)2, is a double salt
A double salt is a salt that contains two or more different cations or anions. Examples of double salts include alums (with the general formula ) and Tutton's salts (with the general formula ). Other examples include potassium sodium tartrate, a ...
of potassium iodate and iodic acid and an acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
as well.
Natural occurrence
Minerals containing iodate are found in the caliche
Caliche () is a sedimentary rock, a hardened natural cement of calcium carbonate that binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions ...
deposits of Chile. The most important iodate minerals are lautarite
Calcium iodate is any of two inorganic compounds with the formula Ca(IO3)2(H2O)x, where x = 0 or 1. Both are colourless salts that occur as the minerals lautarite and bruggenite, respectively. A third mineral form of calcium iodate is dietzeite, ...
and brüggenite, but also copper-bearing iodates such as salesite are known.
References
{{reflist
Halates