[chmdummy1982]

Hi. I am trying to solve a couple of chemistry problems relating to using the empirical formula and am struggling with it. Can someone show me how they would do it.

Here they are:

A hydrocarbon mixture consists of 88.89% carbon and 11.11% hydrogen by mass. What is the empirical formula of the hydrocarbon?

If the molecular weight of the hydrocarbon is approximately 54 g/mol, what is the molecular formula?



Thanks!

[Astrokel]

There are many online tutorials to this. Google: http://chemistry.about.com/od/workedchemistryproblems/a/empirical.htm

[Vidya]

first take out % of oxygen.
Divide each % by its atomic mass to take out the mole ratio of each atom.get the smallest ratio and that will give you empirical formula.Try it.I have given you simple outline.Divide molar mass with empirical formula mass to get the number n
(Empirical formula)n  =  molecular formula

[Doom91]

the answer should be C4H6 and it should be butadiene

[Vidya]

yes C4H6 is correct formula
But you can not be sure of it name ,it can be Butyne .So don't predict functional groups.