Summary:
- Mass-mass calculations are the most practical of all mass-based stoichiometry problems.
- Moles cannot be measured directly, while the mass of any substance can generally be easily measured in the lab.
- The mass of the given substance is converted into moles by use of the molar mass of that substance from the periodic table.
- The moles of the unknown are converted to mass by using the mole ratio from the balanced chemical equation.
- Each answer has three significant figures, as shown below.