Question

A compound contains only carbon, hydrogen, and oxygen. Combustion of 54.05 g of the compound yields 79.22 g of CO₂ and 32.43 g of H₂O.
The molar mass of the compound is 120.104 g/mol.

*Each part of this problem should be submitted separately to avoid losing your work*

1. Calculate the grams of carbon (C) in 54.05 g of the compound:  grams
2. Calculate the grams of hydrogen (H) in 54.05 g of the compound.  grams
3. Calculate the grams of oxygen (O) in 54.05 g of the compound.  grams

There is 1 mole of C present in CO2 and 12.01 g of C in 1 mole of C. Starting with 79.22 g of CO2, set up your equation so the units cancel and only grams of C remain. All the carbon that came from the compound ended up as carbon in the 79.22 g of CO2 produced in the combustion reaction. Remember, there is 44.01 g of CO2 in 1 mole of CO2. By sig fig rules, your answer should have four sig figs. There are 2 moles of H present in H2O and 1.008 g of H in 1 mole of H. Starting with 32.43 g of H2O, set up your equation so the units cancel and only grams of H remain. Use 18.02 for the molar mass of water and by sig fig rules, your answer should have four sig figs. To find how many grams of oxygen you have, subtract the mass of C and H you calculated above from the total mass of the compound. By sig fig rules, your answer should be rounded to two decimal places.

Based on your previous answers, calculate

1. the moles of carbon (C) in 54.05 g of the compound:  moles
2. the moles of hydrogen (H) in 54.05 g of the compound:  moles
3. the moles of oxygen (O) in 54.05 g of the compound:  moles

Divide each mole quantity that you determined in the previous question by the smallest number of moles to determine the correct empirical formula.

Enter the correct subscript for each atom using the smallest whole number.
Enter a 1 if that is the smallest whole number, don't leave the box empty. C  H  O  

Now determine the molecular formula. Remember that the molar mass of the compound is 120.104 g/mol.

Enter the correct subscript for each atom using the smallest whole number.
Enter a 1 if that is the smallest whole number, don't leave the box empty.

C_  H_  O_

Answer 1