Why is the general formula for alkanes... Help me out please?

Question

If the structural until of alkanes is -CH2-, containing one carbon and two hydrogen atoms, why is the general formula for alkanes CnH2n+2?

Answer 1

There is not such structure as CH2

Answer 2

The structural unit of the alkane is CH2 which is CnH2n. The extra +2 comes from the two extra H atoms on the two terminal carbons.

You have

H3C - (CH2)n - CH3 or   H - (CH2)n - H

Answer 3

It means that it has to stay at a 1 Carbon : 2 Hydrogen ratio.  The n stands for whatever number of CH2's there are, and the n+2 says that for each n Carbon, you'll have n+2 H2's attached to it.

So, if n=3

C3H6

if n=5

C5H10

if n=10

C10H20