Combustion analysis problem? - General Chemistry

[joe823]

Homework Statement

When a sample that is .91 grams is burned in oxygen, it produces 2.073 grams of carbon dioxide, .304 grams of water, and .0944 grams of nitrogen. What is the empirical formula of the compound?

The Attempt at a Solution

I converted all of the products to moles:
CO₂: .0471 moles
H₂O: .0169 moles
N₂: .00337 moles.

This gave me C_.0471H_.0338N_.00674.

Simplifying the ratios, I got C₇H₅N.

My problem is that I don't have any idea of what to do with the oxygen. I don't even know if/how much of it it is present in the sample, because the sample is burned.

Thanks in advance for any help.

 

[Ygggdrasil]

From the amounts of carbon dioxide, water, and nitrogen produced, you should be able to figure out the mass of carbon, hydrogen and nitrogen in the original sample. The remaining mass is presumably due to oxygen.

 

[Blueshift5]

I would first check if the combustion reaction is balanced. If it is, then the amount of oxygen consumed in the reaction can be calculated based on the stoichiometry of the balanced equation. This information can then be used to determine the empirical formula of the compound.

If the reaction is not balanced, then the products and reactants need to be balanced before proceeding with the calculation. Another thing to consider is the possibility of impurities in the sample that could affect the results of the combustion analysis.

In any case, it is important to double check all calculations and make sure they are consistent with the data provided. If there are still discrepancies, it may be necessary to repeat the experiment or seek the assistance of a chemistry expert.