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How to balance a chemical equation

Balancing chemical equations means making the same number of each atom appear on both sides. Learn the steps with a worked example.

A balanced chemical equation has the same number of each type of atom on both sides.

Steps

  1. Write the unbalanced equation with correct formulas.
  2. Count atoms of each element on both sides.
  3. Adjust coefficients (the numbers in front of formulas) — never change subscripts.
  4. Re-count until every element balances.

Worked example

Balance: CH4+O2→CO2+H2O\text{CH}_4 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}

  • Carbon: 1 on each side already.
  • Hydrogen: 4 on the left, 2 on the right. Put a 2 in front of H2O\text{H}_2\text{O}.
  • Oxygen: now 2 on the left, 4 on the right. Put a 2 in front of O2\text{O}_2.

CH4+2O2→CO2+2H2O\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}

Practise balancing randomised equations below.

Put it into practice

Practise this topic with questions and get an explanation after each answer.

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