Difference between revisions of "Iodic acid"
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Revision as of 11:46, 10 September 2010
Iodic acid | |
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IUPAC name | iodic acid |
Identifiers | |
InChI | InChI=InChI=1S/HIO3/c2-1(3)4/h(H,2,3,4) |
InChIKey | ICIWUVCWSCSTAQ-UHFFFAOYAT |
Standard InChI | InChI=1S/HIO3/c2-1(3)4/h(H,2,3,4) |
Standard InChIKey | ICIWUVCWSCSTAQ-UHFFFAOYSA-N |
CAS number | [ ] |
EC number | |
ChemSpider | |
Properties[1][2] | |
Chemical formula | HIO3 |
Molar mass | 175.91 g mol−1 |
Appearance | white crystals |
Density | 4.629 g cm−3 |
Melting point |
100 °C decomp. |
Solubility in water | 286 g/100 ml (0 °C) 473 g/100 ml (80 °C) |
Acidity (pKa) | 0.804 |
Structure[1] | |
Molecular geometry | pyramidal; r(I=O) = 181 pm, r(I–OH) = 189 pm, O=I=O = 101.4°, O=I–OH = 97° |
Hazards[3] | |
EU index number | not listed |
GHS pictograms | |
GHS signal word | DANGER |
GHS hazard statements | H272, H314, H318 |
GHS precautionary statements | P210, P220, P221, P260, P264, P280, P301+330+331, P303+361+353, P363, P304+340, P310, P321, P305+351+338, P370+378 |
Flash point | non-flammable |
Related compounds | |
Other anions | Hydriodic acid Periodic acid |
Other compounds | Chloric acid Bromic acid |
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
Iodic acid, HIO3, is a moderately strong oxoacid of iodine. It forms a series of salts called iodates.
Iodic acid may be prepared by the oxidation of suspensions of iodine in water, either by electrolysis or with nitric acid.[1] Unlike chloric and bromic acids, it can be isolated as a white crystalline air-stable solid. The solid decomposes on heating, first to HIO3·I2O5 at about 100 °C, then to iodine pentoxide at about 200 °C.[1]
Iodic acid is used as primary standard strong acid in acid–base titrations because it can be weighed as a pure solid and has a relatively high molar mass. However, the solid cannot be dried in a 110 °C oven because of dehydration, and recrystallization is difficult because of the high solubility of HIO3: for these reasons, potassium biiodate is usually preferred as a strong-acid standard.
Notes and references
Notes
References
- ↑ 1.0 1.1 1.2 1.3 Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; p 1010. ISBN 0-08-022057-6.
- ↑ CRC Handbook of Chemistry and Physics, 62nd ed.; Weast, Robert C., Ed.; CRC Press: Boca Raton, FL, 1981; p B-106. ISBN 0-8493-0462-8.
- ↑ HSNO Chemical Classification Information Database, <http://www.ermanz.govt.nz/Chemicals/ChemicalDisplay.aspx?SubstanceID=12620> (accessed 9 September 2010), New Zealand Environmental Risk Management Authority.
External links
See also the corresponding article on Wikipedia. |
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