Question

Give a test that can be used to differentiate chemically between butter and cooking oil.

                  OR  

Give a chemical test to distinguish between butter and cooking oil.

Answer 1

i. Butter generally has saturated carbon chains while cooking oil generally has unsaturated carbon chains.
ii. Unsaturated hydrocarbons undergo hydrogenation (i.e.,addition of H2) in presence of a catalyst such as nickel or palladium.
iii. Thus, cooking oil can be hydrogenated to form fats (vanaspati ghee) while butter cannot be hydrogenated.

Note: The presence of unsaturation (in cooking oil) can be detected using bromine water test.