Pertechnetic acid
Pertechnetic acid is a compound of technetium that is produced by reacting technetium oxide with water or strong oxidizing acids, such as nitric acid, concentrated sulfuric acid, aqua regia. The dark red hygroscopic substance is a strong acid, with a pKa of 0.32, as such it exists almost entirely as the pertechnetate ion in aqueous solution.
Use of strong enough acid solution, for example, concentrated sulfuric acid, can generate the protonated form, which then exists as the octahedral TcO32 dihydrate complex.
