Iodic acid
| Names | |
|---|---|
| IUPAC name
Iodic acid
| |
| Preferred IUPAC name
Iodic acid | |
| Systematic IUPAC name
Iodic acid | |
| Other names
Iodic(V) acid
Trioxoiodic(V) acid | |
| Properties | |
| HIO3 | |
| Molar mass | 175.91 g/mol |
| Appearance | White solid |
| Odor | Odorless |
| Density | 4.62 g/cm3 (20 °C) |
| Melting point | 110 °C (230 °F; 383 K) [4] |
| Boiling point | 200 °C (392 °F; 473 K) (decomposes) |
| 236.7 g/100 ml (0 °C) 253.4 g/100 ml (16 °C) 280.2 g/100 ml (40 °C) 360.8 g/100 ml (100 °C)[1][2] | |
| Solubility | Soluble in sulfuric acid Moredately soluble in ethanol, methanol Insoluble in glacial acetic acid, carbon disulfide, chloroform, diethyl ether, perchloric acid[3] |
| Vapor pressure | ~0 mmHg |
| Acidity (pKa) | 0.75 |
| Thermochemistry | |
| Std enthalpy of
formation (ΔfH |
-243.1 kJ/mol |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Flash point | Non-flammable |
| Related compounds | |
| Related compounds
|
Chloric acid Bromic acid Periodic acid |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Iodic acid is a chemical compound, a solid inorganic acid with the chemical formula HIO3. Unlike its other halogen equivalents, namely chloric acid and bromic acid, iodic acid is one of the most stable oxo-acids of the halogens.
Contents
Properties
Chemical
Iodic acid is a relatively strong acid with a pKa of 0.75. It is strongly oxidizing in acidic solution, less so in basic solution. When iodic acid acts as oxidizer, then the product of the reaction is either iodine, or iodide ion.
When iodic acid is added to an aq. solution of sodium hydroxide, sodium iodate is produced.
- HIO3 + NaOH → NaIO3 + H2O
When heated to 200 °C, iodic acid dehydrates to give iodine pentoxide. If excess heat is used, the resulting iodine pentoxide further decomposes to iodine and oxygen.
- 2 HIO3 → I2O5 + H2O
- I2O5 → I2 + 5/2 O2
Physical
Iodic acid is a white solid, very soluble in water.
Availability
Iodic acid is sold by chemical suppliers. Can also be bought online.
Preparation
Iodic acid can be produced by oxidizing elemental iodine with chlorine, in water.
- I2 + 6 H2O + 5 Cl2 ⇌ 2 HIO3 + 10 HCl
Other oxidizers, such as nitric acid[5][6], chloric acid[7], bromine[8], ozone[9][10] or hydrogen peroxide[11] can also be used.[12]
Addition of iodine trichloride to water will produce iodic acid and other side products, depending on the temperature:
- 2 ICl3 + 3 H2O → 5 HCl + HIO3 + ICl (cold water)
- 5 ICl3 + 9 H2O → 15 HCl + 3 HIO3 + I2 (hot water)
Adding iodine pentoxide to water will form very pure iodic acid.[13]
- I2O5 + H2O → 2 HIO3
Very pure and concentrated iodic acid can also be produced by adding concentrated sulfuric acid to calcium or barium iodate, with the resulting insoluble calcium and barium sulfate being filtered off.[14][15]
- Ca(IO3)2 + H2SO4 → 2 HIO3 + CaSO4
- Ba(IO3)2 + H2SO4 → 2 HIO3 + BaSO4
Adding elemental iodine to an aq. solution of silver iodide and heating the solution will precipitate silver iodide and yield iodic acid.[16]
Reduction of periodic acid with a suitable reducing agent, such as aq. sulfur dioxide will yield iodic acid.[17]
Adding nitrogen trichloride to an aq. suspension of iodine is described as producing iodic acid.[18]
Projects
- Make iodate salts
- Make iodine pentoxide
Handling
Safety
Iodic acid is irritant, corrosive and oxidizer. Wear proper protection when handling the compound.
Storage
In closed glass bottles.
Disposal
Can be reduced to iodide if necessary using a reducing agent.
References
- ↑ Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977 (Rabinovich V.A., Khavin Z.Ya. A short chemical reference book. - L .: Chemistry, 1977)
- ↑ Справочник по растворимости. - Т.1, Кн.1. - М.-Л.: ИАН СССР, 1961 (Solubility Handbook. - Vol. 1, Book 1. - M.-L .: IAN USSR, 1961 )
- ↑ Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977 (Rabinovich V.A., Khavin Z.Ya. A short chemical reference book. - L .: Chemistry, 1977 )
- ↑ Baxter, G. P.; Tilley, G. St.; Journal of the American Chemical Society; vol. 31; (1909); p. 205
- ↑ Scott, A.; Arbuckle, W.; Journal of the Chemical Society; vol. 79; (1901); p. 302
- ↑ Perez-Vitoria, A.; Garrido, J.; Anales de la Real Sociedad Espanola de Fisica y Quimica; vol. 30; (1932); p. 13
- ↑ Lamb; Bray; Geldard; Journal of the American Chemical Society; vol. 42; (1920); p. 1636 - 1636
- ↑ Bugarszky, St.; Horvath, B.; Z. Anorg. Chem.; vol. 63; (1909); p. 184
- ↑ Engler, C.; Wild, W.; Ber.; vol. 29; (1896); p. 1929
- ↑ Biedermann, Georg; Lendeus, Roland; Acta Chemica Scandinavica, Series A: Physical and Inorganic Chemistry; vol. 38; (1984); p. 825 - 827
- ↑ Bray, W. C.; Caulkins, A. L.; Journal of the American Chemical Society; vol. 53; (1931); p. 44
- ↑ Holleman, Arnold F.; Wiberg, Nils (2007). Lehrbuch der Anorganischen Chemie (in German) (102nd ed.). Berlin
- ↑ IODINE Its Properties and Technical Applications, CHILEAN IODINE EDUCATIONAL BUREAU, INC., 120 Broadway, New York 5, New York, 1951
- ↑ Reichardt, E.; Archiv der Pharmazie (Weinheim, Germany); vol. 205; (1874); p. 109 - 111
- ↑ Stevenson, W.; Chem. News J. Ind. Sci.; vol. 36; (1877); p. 201
- ↑ Naquet, A.; Bulletin de la Societe Chimique de France; (1858); p. 126 - 129
- ↑ Selmons, F.; Ber.; vol. 21; (1888); p. 230
- ↑ Sseliwanow; Zh. Russ. Fiz. - Khim. O - va., Chast Khim.; vol. 26; (1894); p. 541 - 541
