Chemistry – Experimental techniques and chemical analysis - Separation and purification | e-Consult

A suitable technique is sublimation.

Scientific Principle: Sublimation is the process where a solid changes directly into a gas without passing through the liquid phase. Iodine has a relatively high vapour pressure at room temperature, meaning it readily sublimes.

Procedure: The aqueous solution of iodine, potassium iodide and chlorine would be heated gently. The iodine will sublime and deposit as a solid on a cool surface (e.g., the inside of a test tube or a cold finger). The potassium iodide will remain dissolved in the water, and the chlorine will be present as a gas. The solid iodine can then be collected.

Why this is suitable: Sublimation effectively separates iodine from the other components because the other substances (potassium iodide and chlorine) do not sublime readily under these conditions. The purity of the obtained iodine can be further improved by repeated sublimation.