Question

What are the condensed formulas of the five isomers of C6H14?

Answer 1

`"H"_3"C"("CH"_2)_4"CH"_3`
`"H"_3"C"("CH"_2)_3"(CH"_3)_2`
`"HC"("CH"_3)("CH"_2"CH"_3)_2`
`("H"_3"C")_2"CHCH"("CH"_3)_2`
`"C"("CH"_3)_3("CH"_2"CH"_3)`

Explanation:

We know that the compound is an acyclic alkane, since it has chemical formula of the `"C"_n color(white)(*) "H"_(2n+2)`, where `n` is 6 in this case.

There are only a finite number of such alkanes.

To avoid missing out on any, it pays to do things systematically. I usually go in decreasing length of longest carbon chain.

So first it is longest carbon chain = 6, which corresponds to n-hexane. Then I go for longest carbon chain = 5, which are the 2-methylpentane and 3-methylpentane. And so on.

The names of the above list:

• n-hexane
• 2-methylpentane
• 3-methylpentane
• 2,3-dimethylbutane
• 2,2-dimethylbutane

respectively