Hazard
Toxic by ingestion, strong irritant to eyes
and skin.
Chemical Properties
colorless, rhomb crystal(s) or white, crystal(s) powder(s); darkens on exposure to light; it is a moderately strong acid; used in analytical chemistry and in medicine [HAW93] [MER06]
Definition
iodic acid: Any of various oxoacids of iodine, such as iodic(V) acid and iodic(VII) acid. When used without an oxidation state specifled, the term usually refers to iodic(V) acid (HIO3).
General Description
Iodic acid is the hydrated form of I2O5. Reaction of iodic acid with hydrogen iodide has been described by electrolytic dissociation theory. Combustion of mixture of chromic, iodic, sulfuric and phosphoric acids has been proposed. Its Raman spectra have been recorded. Vibrational assignment of IO3- has been evaluated.
Purification Methods
Dissolve iodic acid in the minimum volume of hot dilute HNO3, filter and evaporate in a vacuum desiccator until crystals are formed. Collect the crystals and wash them with a little cold H2O and dry them in air in the dark. It is soluble in H2O: 269g/100mL at 20o and 295g/100mL at 40o. It is soluble in dilute EtOH and darkens on exposure to light. It is converted to HIO3.I2O5 on heating at 70o, but at 220o complete conversion to HIO3 occurs. [Lamb et al. J Am Chem Soc 42 1636 1920, Bray & Caulkins J Am Chem Soc 53 44 1931.]