Chrominfo: Identification test for iodine

Learn the identification test for iodine through a laboratory experiment or practical.

Aim:

To perform an identification test for iodine.

Reference: Indian Pharmacopoeia (IP)

Requirements:

Glasswares and miscellaneous:

Test tube, measuring cylinder, pipette, glass rod, volumetric flask, beaker, funnel, dropper, rubber stopper, test tube stand, test tube holder, balance, etc.

Chemicals:

Iodine (I2), potassium iodide (KI), starch mucilage, etc.

Theory:

Identification tests are used to determine the drug's quality so that it can be used safely. The chemical element iodine has the symbol I and the atomic number 53. Iodine is the fourth halogen in the periodic table, belonging to group 17 below fluorine, chlorine, and bromine; it is the heaviest and most stable member of its group. It is freely soluble in chloroform, ether, and carbon disulfide, soluble in ethanol, and slightly soluble in water.

Procedure of identification tests for iodine:

When iodine is slowly heated, violet vapors are produced, which condense to form a blue-black crystalline sublimation.
In a solution of potassium iodide, dissolve 2-4 drops of iodine crystals and add a few drops of starch mucilage. When you boil it, it turns a deep blue color that fades away but reappears when you cool it.