Which of the following hydrocarbons undergo addition reaction: #C_2H_6#, #C_3H_8#, #C_3H_6#, #C_2H_2# and #CH_4#?

1 Answer
P dilip_k · Ernest Z.
Apr 9, 2016

#"C"_3"H"_6# and #"C"_2"H"_2# undergo addition reactions.

Explanation:

Unsaturated compounds having one or more carbon-carbon double bonds or triple bonds or both type of bonds undergo addition reactions .

For open chain hydrocarbons, the general molecular formula of a saturated compound (alkane category) is #C_nH_(2n+2)#.

The general molecular formula of an aliphatic hydrocarbon with one double bond is #C_nH_(2n)#, and the general molecular formula of a hydrocarbon having one triple bond or two double bonds is #C_nH_(2n-2)#.

Matching with these formulas, we can decide whether the the compound is unsaturated or not.

Here, #C_3H_8=C_3H_(2xx3+2)#, #C_2H_6= C_2H_(2xx2+2)#, and #CH_4=CH_(2xx1+2)#.

All three follow the general formula of a saturated compound, i.e.#CnH_(2n+2)#, so they will not undergo addition reaction

#C_3H_6=C_3H_(2xx3)# follows the general formula #C_nH_(2n)#,
and #C_2H_2=C_2H_(2xx2-2)# follows the general formula #C_nH_(2n-2)#, so they are unsaturated and undergo addition reactions.

Related questions
See all questions in Hydrogenation
Impact of this question
22287 views around the world
You can reuse this answer
Creative Commons License