Chloroosmic acid (also known as hexachloroosmic acid, and dihydrogen hexachloroosmate) is an inorganic
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
with the chemical formula . It exists as a dark
hygroscopic
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...
solid. It forms a hexahydrate.
Synthesis
Hexachloroosmic acid can be prepared by reducing
osmium tetroxide
Osmium tetroxide (also osmium(VIII) oxide) is the chemical compound with the formula OsO4. The compound is noteworthy for its many uses, despite its toxicity and the rarity of osmium. It also has a number of unusual properties, one being that the ...
in
hydrochloric acid
Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...
with alcohol and heating.
is sometimes used in place of alcohol.
: + 4 + 10HCl → + 4 + 4
Another way of preparing it is by dissolving
osmium dioxide
Osmium dioxide is an inorganic compound with the formula . It exists as brown to black crystalline powder, but single crystals are golden and exhibit metallic conductivity. The compound crystallizes in the rutile structural motif, i.e. the connec ...
in hydrochloric acid.
It can also be prepared by reducing
potassium osmate
Potassium osmate is the inorganic compound with the formula K2 sO2(OH)4 This diamagnetic purple salt contains osmium in the VI (6+) oxidation state. When dissolved in water a red solution is formed. When dissolved in dilute alcohols, the salt give ...
with hydrochloric acid under heating.
Properties
Solid crystals of hexachloroosmic acid have been described as reddish-purple in color, while commercial vendors describe it as black. In solution, it exhibits colors ranging from yellowish green to reddish brown. Owing to its highly hygroscopic nature, solutions of hexachloroosmic acid can be evaporated down to a syrup without crystallization. As an acid, it is corrosive.
Reactions
When strong alkali is added to hexachloroosmic acid, it decomposes and precipitates osmium dioxide.
It also reacts with alkali chlorides to yield hexachloroosmate salts, such as
ammonium hexachloroosmate(IV)
Ammonium hexachloroosmate(IV) is an inorganic chemical compound with the chemical formula .
Synthesis
Ammonium hexachloroosmate(IV) can be produced by the reduction of osmium tetroxide or potassium osmate with iron dichloride in hydrochloric acid ...
.
References
{{Osmium compounds
Hydrogen compounds
Osmium_compounds
Chlorometallates