Edexcel IGCSE Chemistry · Spec 1.31-1.36
Empirical & Molecular Formulae
How to work out empirical and molecular formulae from experimental data.
Chemistry revision video
Empirical & Molecular Formulae
Prefer to watch on YouTube? Open this video on YouTube.
Spec 1.31-1.36
What you need to know
- Tell the difference between an empirical and a molecular formula
- Work out an empirical formula from masses
- Find the formula of an oxide by experiment
Active recall
Quick check
Answer each question before opening the answer.
What is the difference between an empirical and a molecular formula?
Empirical formula is the simplest whole-number ratio of atoms; molecular formula is the actual number of each atom in a molecule.
How do you find an empirical formula from masses or percentages?
Divide each element's mass/percentage by its Ar, then divide all answers by the smallest to get the simplest ratio.
Chemistry video companion
Keep your notes and exam practice together
The free Chemistry workbook follows every video in specification order.