# Empirical Formula

1. The empirical formula of a substance is the chemical formula that gives the simplest whole-number ratio of atoms of each element in the substance.
2. Empirical = information gained by means of observation, experience, or experiment.
Example:
 Chemical Substances Molecular Formula Empirical Formula Glucose C6H12O6 CH2O Water H2O H2O Carbon Dioxide CO2 CO2 Benzene C6H6 CH Butane C4H8 CH2

### Finding Empirical Formula

Steps to determine the empirical formula of a compound
STEP 1: Find the mass
STEP 2: Find the mole
STEP 3: Find the simplest ratio

Example:
In a chemical reaction, 4.23g of iron reacts completely with 1.80g of oxygen gas, producing iron oxide. Calculate the empirical formula of iron oxide. [Relative atomic mass: Iron = 56; Oxygen = 16]

 Element Fe O Mass 4.23g 1.80g Number of mole $4.23 56 =0.0755$ $1.80 16 =0.1125$ Simple ratio $0.0755 0.0755 =1$ $0.1125 0.0755 =1.5$ Ratio in round number 2 3