[kevinkevin]

  Ok, we skipped this in my last chemistry class and now it is has surfaced again in AP chemistry. 
Here is the question...
   
   A compound contains the elements carbon, hydrogen and nitrogen.  When 0.1156g of this compound is reacted with oxygen in a combustion device, 0.1638g of carbon dioxide and 0.1676g of water are collected.  Determine the empirical formula of this compound.

    Ok, I am aware of the rules of the forum and here is where I think you start... i have no idea.  I do not know what i halft to find the masses for (if i even do) or any other steps that may need to be taken.  All help appricated, thanks. 

 

[sjb]

  Ok, we skipped this in my last chemistry class and now it is has surfaced again in AP chemistry. 
Here is the question...
   
   A compound contains the elements carbon, hydrogen and nitrogen.  When 0.1156g of this compound is reacted with oxygen in a combustion device, 0.1638g of carbon dioxide and 0.1676g of water are collected.  Determine the empirical formula of this compound.

    Ok, I am aware of the rules of the forum and here is where I think you start... i have no idea.  I do not know what i halft to find the masses for (if i even do) or any other steps that may need to be taken.  All help appricated, thanks. 

http://www.google.com/cse?q=empirical+formula&siteurl=www.chemicalforums.com , perhaps?

[Arkcon]

Try to begin to work this out backwards from the products.  Those masses of carbon dioxide and water are how many moles?  Once you have that, you know the coefficients of a products in a balanced chemical reaction.  They try to write it so it makes sense, given mass of reactant, and all the oxygen you feel like adding (because that's what the "combustion device" does -- gives it all the oxygen it needs.)  Even 'tho you missed this class, some examples should be available in your textbook.

[Vidya]

mass of CO2----> moles of CO2------> moles of C ---> mass of C -->%  C in the sample
mass of H2O----> moles of H2O------> moles of H ----mass of H ---> % H in the sample
% N = 100-(%C+%H)
%N ---> mass of N ---> moles of N
now you have
moles of C,H and N
take out the simplest ratio by diving moles of C,H and N by the smallest number of moles.
this will give you empirical formula