To understand the exercise, we first need to calculate the molar mass of the substances involved: carbon dioxide (
CO₂) and propane (C₃H₈). The molar mass of a compound is determined by adding up the atomic masses of all the atoms in a molecule. This is essentially the mass of one mole of that compound.
For carbon dioxide, the chemical formula is COâ‚‚. It consists of one carbon atom and two oxygen atoms. Carbon has an atomic mass of 12.01 g/mol, and oxygen has an atomic mass of 16.00 g/mol. By adding these together, the molar mass of COâ‚‚ becomes:
- Molar mass of carbon: 1 × 12.01 g/mol = 12.01 g/mol
- Molar mass of oxygen: 2 × 16.00 g/mol = 32.00 g/mol
- Total molar mass of COâ‚‚ = 12.01 + 32.00 = 44.01 g/mol
For propane (C₃H₈), the molecule consists of three carbon atoms and eight hydrogen atoms. Hydrogen has a smaller atomic mass of 1.01 g/mol, so the calculation is:
- Molar mass of carbon: 3 × 12.01 g/mol = 36.03 g/mol
- Molar mass of hydrogen: 8 × 1.01 g/mol = 8.08 g/mol
- Total molar mass of propane = 36.03 + 8.08 = 44.11 g/mol
Understanding how to calculate molar mass is crucial in applying Graham's Law of Effusion, which deals with how gases escape through a tiny opening.