Question

How to determine the number of isomerism in alkanes?

Answer 1

It can easily be determined.
Just do branching like 1 branching,2 branching...and go on.Count how many unique branching you have got and get the isomers.

Hope it was helpful.

Regards,
Adithiya

Answer 2

Unfortunately, there is no formula to calculate the number of structural isomers of an alkane. This is mainly due to the fact that with a certain number of carbons, they can branch out (although most are unstable and do not actually exist).

For example, the formula C4H10 represents both butane and 2-methylpropane (both are stable in similar SCTPs) :




The first ten are: 

Number of carbons   ->  Number of structural isomers
0 -> 1
1 -> 1
2 -> 1
3 -> 1
4 -> 2
5 -> 3
6 -> 5
7 -> 9
8 -> 18
9 -> 35
10 -> 75