Question

What would be considered the molecular formula for the compound that has an empirical formula of `CH_4` but a molar mass of 80 g/mol?

Answer 1

Empirical formula means the ratio `CdivH=1div4`

Explanation:

If we translate this to atomic mass units, the ratio goes to:
`1xx12div4xx1=12div4`

The sum of the ratios is `16` and this goes into `80` five times.

So the molecular formula would be `C_(1xx5)H_(4xx5)=C_5H_20`

Check : `5xx12+20xx1=80`

Note : This is a non-existing compound, as `5C` atoms can at most hold `12H` atoms (matter of valencies).