Empirical formula

Empirical formula refers to the simplest positive integer ratio of atoms present in a compound. It is a type of chemical formula that provides the simplest whole number ratio of the atoms of each element present in a compound, but does not provide any information about the absolute number of atoms in a molecule.

Overview

The empirical formula is used in chemistry to denote the simplest ratio of elements in a compound. Unlike the molecular formula, which shows the exact number of atoms of each element in a molecule, the empirical formula only shows the ratio of atoms. For example, the molecular formula for glucose is C6H12O6, but its empirical formula is CH2O, which shows the simplest whole number ratio of carbon, hydrogen, and oxygen atoms.

Calculation

The empirical formula of a compound can be determined from the percent composition of each element in the compound. The steps to calculate the empirical formula are as follows:

1. Convert the percentage composition of each element to grams.
2. Convert the mass of each element to moles.
3. Divide the number of moles of each element by the smallest number of moles calculated.
4. Round the ratio to the nearest whole number to get the empirical formula.

Examples

Some examples of empirical formulas include:

• Water (H2O): The empirical formula is the same as the molecular formula.
• Hydrogen peroxide (H2O2): The empirical formula is HO.
• Ethene (C2H4): The empirical formula is CH2.

See also

• Molecular formula
• Chemical compound
• Chemical formula
• Mole (unit)