Empirical & Molecular formulas of compounds

Question

Cannizzaro determined that a certain compound of carbon and oxygen had a molecular mass of 44.0 u. This meant that a certain volume of this gaseous compound weighed 44.0 times as much as the same volume of hydrogen gas at the same temperature and pressure. This compound was analyzed and found to be 27.3% carbon by mass.

 

a) What is the total mass of carbon in a molecule of this compound 

 

b) The experiment was repeated on many carbon compounds. Because he never found a molecule with less carbon than this one, Cannizzaro assumes that this molecule has only one carbon atom. Was this assumption correct?

 

I am confused about what to do with the molar mass

Answer 1

If the molecular mass of the unknown is 44.0 u, and it is 27.3% C, then the mass of C = 0.273 x 44.0 = 12.0 u.

 

Yes, his assumption is correct, because 1 mole of this compound contains exactly 1 mole of C (atomic mass of 12.01).