Chevreul's Salt

Chevreul's Salt is an inorganic compound with the chemical formula Cu3H4O8S2. It is a brick red solid which is insoluble in water. It is unusual in that it contains copper in both of its main oxidation states, 1+ and 2+.It was was prepared for the first time by a French chemist named Michel Eugène Chevreul in 1812.

Synthesis
Chevreul's salt is prepared by treating an aqueous solution of copper(II) sulfate with a solution of potassium metabisulfite. The solution changes colour from blue to green immediately. The identity of the green species is unknown. Heating this solution produces a reddish solid precipitate.

Reactions
Chevreul's salt exhibits properties of both copper(I) and copper(II). On reaction with Hydrochloric acid, it produces a white precipitate of copper(I) chloride. If too much acid is added, the precipitate dissolves. If an ammonia solution is added to the product, it is dissolved and a deep blue color appears, which is due to the presence of the tetraamminecopper(II) complex. __INDEX__