The copper(II)sulphate is reccovered and used to precipitate more copper(I)iodine.
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 iodine solution,in which the iodine is composed of I2 molecules up to about 1000K;above this temperature,dissociation into iodine atoms becomes appreciable
Like bromine,iodine is soluble 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 splution is formed,whilst a violet solution is produced in csrbon disulphide and some hydrocarbons. These colours arise due to charge transfer (p.60)to and from the iodine and the solvent organic molecules