With the help of an example, explain the process of hydrogenation. Mention the essential conditions for the reaction and state the change in physical property with the formation of the product.

Explanation

The addition of hydrogen to an unsaturated hydrocarbon to get a saturated hydrocarbon is called hydrogenation.
Example : Vegetable oils such as groundnut oils, cotton seed oils and mustard oils are unsaturated and also contain double bonds (C=C). They are in the liquid state. On hydrogenation (addition of hydrogen) in the presence of nickel as catalyst vegetable oil produces vanaspati ghee. This is solid at room temperature.

The essential condition for the reaction is presence of nickel as a catalyst and temperature.
Change observed in the physical property during hydrogenation is the change of the unsaturated compound from the liquid state to the corresponding saturated compound in the solid state/its boiling on melting point will increase.