Question

how is substitution reaction in alkanes different from dehydrogenation reaction since both involve removing a hydrogen atom from the molecule?

Answer 1

See Explanation

Step-by-step explanation:

A substitution reaction means the replacement of one or more hydrogen atoms in an alkane by another atom or group. It does not introduce a double bond into the product. The product retains single bonds between the species present.

For instance;

CH4 + Cl2 -------> CH3Cl +HCl

is a substitution reaction

Dehydrogenation is the process of removing two hydrogen atoms from a saturated compound compound thereby yielding an unsaturated product.

E.g

C2H6 --------->C2H4 + H2

The key difference is that substitution reaction yields a saturated product while dehydrogenation yields an unsaturated product.