Question

How can we identify ethane from ethene?

Answer 1

Saturated hydrocarbons:-

• A hydrocarbon where there is only the presence of only single bond between the carbons atoms is called saturated hydrocarbon.
• They are also called alkanes
• The general formula for saturated hydrocarbons are${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}+2}$.
• An example is: Ethane $({\mathrm{CH}}_3-{\mathrm{CH}}_3)$

Unsaturated hydrocarbons:-

• A hydrocarbon where there is the presence of a double or triple bond between the carbons atoms is called an unsaturated hydrocarbon.
• They are also called alkenes and alkynes.
• The general formula for unsaturated hydrocarbons are${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}-2}$(alkenes), ${\mathrm{C}}_{\mathrm{n}}{\mathrm{H}}_{2\mathrm{n}}$(alkynes)
• An example is: Ethene $({\mathrm{CH}}_2={\mathrm{CH}}_2)$

Test to differentiate between Ethane and Ethene:-

• We use the bromine water test in order to distinguish between Ethane and Ethene.
• Bromine water is nothing but bromine in water.
• When bromine water is treated with Ethene, the bromine gets attached to the hydrocarbon and thus the red-brown colour of bromine gets decolorized.

• On the other hand, when bromine water is reacted to Ethane, the red-brown colour of bromine does not get decolorized.

Therefore, to differentiate between ethane and ethene, we use the bromine water test.