Question

What is the molecular formula of each compound CH2 with molar mass 42.08 g/mol?

Answer 1

Don't we got `C_3H_6`...I,e, probably propylene...

Explanation:

The `"empirical formula"` is the simplest, whole number ratio defining constituent atoms in a species. The `"molecular formula"` is a whole number multiple of the `"empirical formula"`, and of course the multiple MIGHT be ONE.

And thus....`"molecular formula"=nxx{"empirical formula"}`

And we take the relevant masses...

`[(2xx12.011+4xx1.00794)*g*mol^-1]xxn-=underbrace(42.08*g*mol^-1)_"given molecular mass"`

And so we solve for `n` by the quotient....

`n=(42.08*g*mol^-1)/[1xx12.011+2xx1.00794*g*mol^-1]=3`

And so our molecular formula is `3xxCH_2-=C_3H_6`...this is propylene, or cyclopropane...