Edexcel IGCSE Chemistry · Spec 1.25-1.26
Equations & Relative Formula Mass
Writing balanced chemical equations and calculating relative formula mass.
Chemistry revision video
Equations & Relative Formula Mass
Prefer to watch on YouTube? Open this video on YouTube.
Spec 1.25-1.26
What you need to know
- Write and balance symbol equations
- Use the state symbols
- Calculate a relative formula mass
Active recall
Quick check
Answer each question before opening the answer.
How do you calculate the relative formula mass (Mr) of a compound?
Add up the relative atomic masses (Ar) of all the atoms in its formula.
Why must a chemical equation be balanced?
Because atoms are not created or destroyed — there must be the same number of each atom on both sides (conservation of mass).
Chemistry video companion
Keep your notes and exam practice together
The free Chemistry workbook follows every video in specification order.