It is both chemically and physically addictive.
Caffeine occurs naturally in coffee, tea, and chocolate.
It is slightly soluble in water at room temperature, but highly soluble in water at 100 o C. Chloroform is a nonpolar solvent in which caffeine is highly soluble. Using a combination of the polar solvent water and the nonpolar solvent chloroform, crystals of caffeine can be extracted from tea leaves. Boil the tea in 200 ml of water for 15 minutes. Allow to cool for 15 minutes. Remove the tea leaves and filter the solution.