How to Calculate Empirical Formula
What is Empirical Formula?
The empirical formula of a compound shows the simplest whole-number ratio of atoms of each element present. It is derived from the percentage composition by mass. The molecular formula is a whole-number multiple of the empirical formula.
Step-by-Step Guide
- 1Convert mass percentages to moles by dividing by atomic mass
- 2Divide all mole values by the smallest value to get ratios
- 3If ratios are not whole numbers, multiply all by a small integer (2, 3, or 4)
- 4Write the empirical formula with the resulting whole-number subscripts
Worked Examples
Input
C:40%, H:6.67%, O:53.33%
Result
CH₂O (glucose empirical formula)
C:3.33, H:6.67, O:3.33 → ratio 1:2:1
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