Problem: Upon combustion, a 0.8009 g sample of a compound containing only carbon, hydrogen, and oxygen produces 1.6003 g CO2 and 0.6551 g H2O. Find the empirical formula of the compound.

🤓 Based on our data, we think this question is relevant for Professor Altomare's class at UCF.

FREE Expert Solution

Recall that in combustion analysis, a compound reacts with excess O2 to form products. 


For a compound composed of C, H, and O, the reaction looks like this:


CxHyOz + O2 (excess)  x CO2y H2O


Calculate the mass of C and H.


Mass C:

molar mass of CO2 = 44.01 g/mol


There is 1 mole of C in 1 mole of CO2. Finding the mass of C:


mass of C=1.6003 g CO2×1 mol CO244.01 g CO2×1 mol C1 mol CO2×12.01 g C1 mol C

mass of C = 0.4367 g C


Mass H: 

molar mass of H2O = 18.02 g/mol


There are 2 moles of H in 1 mole of H2O. Finding the moles of H:


mass of H=0.6551 g H2O×1 mol H2O18.02 g H2O×2 mol H1 mol H2O×1.01 g H1 mol H

mass of H = 0.0734 g H



Calculate the mass of O:

 We have 0.8009 g of the sample compound. Subtracting the masses of C and H from this will give us the mass of O:


mass of O = 0.8009 g – (0.4367 g C + 0.0734 g H) = 0.2908 g O



Calculate the moles of each element and determine the lowest whole number ratio. 


moles of C=0.4367 g C×1 mol C12.01 g C

moles of C = 0.0363 mol C

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Problem Details

Upon combustion, a 0.8009 g sample of a compound containing only carbon, hydrogen, and oxygen produces 1.6003 g CO2 and 0.6551 g H2O. Find the empirical formula of the compound.

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Our tutors have indicated that to solve this problem you will need to apply the Combustion Analysis concept. You can view video lessons to learn Combustion Analysis. Or if you need more Combustion Analysis practice, you can also practice Combustion Analysis practice problems.

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Based on our data, we think this problem is relevant for Professor Altomare's class at UCF.