Problem: Combustion analysis of naphthalene, a hydrocarbon used in mothballs, produced 8.80 g CO2 and 1.44 g H2 O.Calculate the empirical formula for naphthalene.

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

FREE Expert Solution

We’re being asked to determine the empirical formula of a compound composed of C and H given the combustion analysis.


Recall that in combustion analysisa 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


This means we need to do the following steps:

Step 1: Calculate the mass of C and H in the compound.

Step 2: Calculate the mass of O in the compound.

Step 3: Determine the lowest whole number ratio of C, H, and O to get the empirical formula.


We can do a mole-to-mole comparison to determine the mass of C and H.


For C: The molar mass of CO2 is:

CO2     1 C × 12.01 g/mol C = 12.01 g/mol             

            2 O × 16.00 g/mol O = 32.00 g/mol     

                                     Sum = 44.01 g/mol


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


mass of C=8.80 g CO2×1 mol CO244.01 g CO2×1 mol C1 mol CO2

mass of C = 0.20 g C


For H: The molar mass of H2O is:

H2O     2 H × 1.01 g/mol H = 2.02 g/mol                  

            1 O × 16.00 g/mol O = 16.00 g/mol     

                                     Sum = 18.02 g/mol


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


mass of H=1.44 g H2O×1 mol H2O18.02 g H2O×1 mol H1 mol H2O

mass of H = 0.08 g H



We next need to calculate the moles of each element and determine the lowest whole number ratio. 


The moles of C and H are:


moles of C=0.20 g C×1 mol C12.01 g C

moles of C = 0.0167 mol C


moles of H=0.08 g H×1 mol H1 g H

moles of H = 0.08 mol H


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Problem Details

Combustion analysis of naphthalene, a hydrocarbon used in mothballs, produced 8.80 g CO2 and 1.44 g H2 O.

Calculate the empirical formula for naphthalene.

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

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.

What professor is this problem relevant for?

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