4
$\begingroup$

I am working on a chemistry assignment and can’t figure out part of the problem.

$0.2\,\mathrm{mol}$ of a compound with a molecular weight of $82$ contain $9.6\,\mathrm{g}$ of carbon, $1.2\,\mathrm{g}$ of hydrogen and the rest is nitrogen.

The question is asking for the empirical and molecular formula which I can solve, but how do you determine the amount of nitrogen?

First I assumed a $100\,\mathrm{g}$ sample but that didn’t get me anywhere. The empirical formula answer is supposed to be $\ce{C2H3N}$ but I couldn’t achieve that. Unless the book is wrong.

$\endgroup$
5
$\begingroup$

If you have $0.2\ \mathrm{mol}$ of a compound with $M_\mathrm{r}=82$, then you have $16.4\ \mathrm{g}$ of material. If there is only carbon, hydrogen and nitrogen present, and the carbon and hydrogen total up to $10.8\ \mathrm{g}$, then the amount of nitrogen must be $16.4\ \mathrm{g}-10.8\ \mathrm{g}=5.6\ \mathrm{g}$.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.