Can the empirical formula of a compound be experimentally found?
The empirical formula of a compound can be experimentally found.
For example, you can do an experiment to determine the empirical formula of magnesium oxide. You heat a known mass of magnesium in a crucible and determine the mass of oxide formed.
Assume that you heated 0.297 g of magnesium and obtained 0.493 g of the oxide. What is the empirical formula of magnesium oxide?
The empirical formula is the simplest whole-number ratio of atoms in a compound.
The ratio of atoms is the same as the ratio of moles. So our job is to calculate the molar ratio of Mg to O.
Mass of Mg = 0.297 g
Mass of oxide = mass of Mg + mass of O
0.493 g = 0.297 g + mass of O
Mass of O = (0.493 – 0.297) g = 0.196 g
Moles of Mg = 0.297 g ×
Moles of O = 0.196 g O ×
There is 1 mol of Mg for 1 mol of O. So
There is 1 atom of Mg for 1 mol of O.
The empirical formula of magnesium oxide is MgO.