The copper(II)sulphate is recovered and used to precipitate more copper(I)iodide.
Iodine and its compounds are. relative to the other halogens.costly substances.
Iodine is a dark-coloured solid which has a glittering crystalline appearance. It is easily sublimed to form a bluish vapour in vacuo but in air,the vapour is brownish-violet. Since it has a small vapour pressure at ordinary temperatures.iodine slowly sublimes if left in an open vessel;for the same reason,iodine is best weighed in a stoppered bottle containing some potassium iodide solution.in which the iodine is composed of molecules up to about 1000K ; above this temperature,dissociation into iodine atoms becomes appreciable.
Like bromine,iodine is solution in organic solvents,for example chloroform,which can be used to extract it from an aqueous solution. The iodine imparts a characteristic purple colour to the organic layer;this is used as a test for iodine (p.349).NB Brown solutions are formed when iodine dissolves in ether,alcohol,and acetone. In chloroform and benzene a purple solution is formed,whilst a violet solution is produced in carbon disulphide and some hydrocarbons. These colours arise due to change transfer(p.60)to and from the iodine and the solvent organic molecules.