Empirical Formula from Mass
This will guide you through determining the Empirical Formula a compound just based on the mass of its parts.
Empirical Formula: The simplest ratio of the atoms present in a molecule.
Problem: Find the empirical formula for the oxide that contains 42.05 g of nitrogen and 95.95 g of oxygen.
As with most stoichiometry problems, it is necessary to work in moles. The ratio of the moles of each element will provide the ratio of the atoms of each element.
- Convert the mass of each element to moles of each element using the atomic masses.
- Find the ratio or the moles of each element by dividing the number of moles of each by the smallest number of moles.
- Use the mole ratio to write the empirical formula.