## anonymous one year ago Caffeine contains C, H, O, N. If the combustion of 1g Caffeine produces 1.813g Co2 and .4639g H2O and the sample contains .2885g 'N'. Estimate the molecular formula of caffeine using the mas spec of caffeine. (mother ion=194) Where do i start?

1. anonymous

Ok so i figured out the mole of C, H, and N C= .0412 mol H= .0514mol N= .02059 mol But i cant seem to figure out O... @aaronq can you please help me

2. anonymous

3. aaronq

sorry, i dont get notifications right away, it's something to do with the site. the moles of O will be half of the moles of $$H_2$$, because in water there are 2 H's and 1 O.

4. anonymous

can you help me with another question @aaronq ?

5. anonymous

$Cu + S_8 \rightarrow ?$ Mass of Cu wire is 1.056g Mass of crucible is 24.681 Copper Sulfide and crucible is 26.033g so Copper sulfide is 1.352 We have to find the empirical formula, which i know how to do, but for some reason this problem is confusing. me. @aaronq

6. anonymous

@paki can you help me?

7. aaronq

so find the mass of S (subtract 1.056 from 1.352) convert both masses (Cu and S) to moles, etc

8. anonymous

So i have .0166mol Cu and .0092mol S Then you divide buy .0092 which gives the empirical formula of Cu2S, correct?

9. anonymous

So the product of Cu + S8 would be Cu2S? Copper (II) sulfide? @aaronq

10. aaronq

if that's what the math says, yes

11. anonymous

Awesome, thanks :)