GIPHOTOSTOCK / SCIENCE PHOTO LIBRARY GIPHOTOSTOCK / SCIENCE PHOTO LIBRARY
Iodine solubility. 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, left to right: water (H2O), cyclohexane (C6H12), dichloromethane (CH2Cl2), and aqueous solution of potassium iodide (KI). 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.
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