Balancing equations

Use whole-number coefficients to balance equations without changing the chemical formulae.

The chemistry

A balanced equation has the same number of atoms of each element on both sides. The substances must also be correct for the stated reaction.

Change the coefficients in front of the formulae. Changing a subscript changes the substance and cannot be used to balance the equation.

Use the smallest whole-number ratio. Enter 1 when a substance needs no larger coefficient. Keep the substances and conditions given in the question.

Hydrogen burns in oxygen to form water.

2 H₂ + O₂ → 2 H₂O: both sides contain four H atoms and two O atoms.

Specification references

AQA 4.3.1.1; Edexcel 0.3

Balanced symbol equations.

Course

Calcium carbonate decomposes when strongly heated.

□ CaCO3 → □ CaO + □ CO2

Balance this equation using the smallest whole-number coefficients. Enter 1 where needed.

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balancing-equations:1.0.0:42:general:gcse-rounded-ar-1:1.0.0

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