Caption:
Iodine solubility, 4 of 4. Iodine (I2) molecule has a covalent non-polar bond. It is only sparingly soluble in polar solvents and is soluble in non-polar solvents. Here iodine solubility in different solvents is demonstrated: water (H2O, Photo 1), cyclohexane (C6H12, Photo 2), dichloromethane (CH2Cl2, Photo 3), and aqueous solution of potassium iodide (KI, Photo 4). In water, iodine stays at the bottom of the test tube and shows only a faint brown colour. Iodine dissolves in non-polar cyclohexane and dichloromethane showing violet and red colours, respectively. Iodine also dissolves in aqueous solution of potassium iodide due to formation of the triiodide ion (I3-), producing red-brown colour.