Balancing Equations Examples in Chemistry

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Balancing Equations.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

The process of adjusting the coefficients (the numbers placed before chemical formulas) in a chemical equation so that the number of atoms of each element.

Atoms can't appear or disappear — every atom on the left must show up on the right.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Conservation of mass — matter is neither created nor destroyed in a reaction.

Common stuck point: Only change coefficients, never subscripts (that changes the substance).

Sense of Study hint: When balancing an equation, work element by element systematically. First list every element that appears in the equation. Then start with elements that appear in only one reactant and one product — balance those first. Finally, balance hydrogen and oxygen last (they tend to appear in multiple compounds), and verify every element is equal on both sides.

Common Mistakes to Watch For

Before you work through the examples, skim the mistake guide so you know which shortcuts and sign errors to avoid.

Balancing Equations Mistakes

Worked Examples

Example 1

easy
Balance the equation: \text{Fe} + \text{O}_2 \rightarrow \text{Fe}_2\text{O}_3.

Solution

  1. 1
    Count atoms — unbalanced: Fe: 1 vs 2, O: 2 vs 3.
  2. 2
    Balance Fe first: put 2 in front of Fe on left. Now: 2\text{Fe} + \text{O}_2 \rightarrow \text{Fe}_2\text{O}_3. Fe balanced.
  3. 3
    Balance O: 2 on left, 3 on right. LCM of 2 and 3 is 6. Use 3\text{O}_2 (gives 6 O) and 2\text{Fe}_2\text{O}_3 (needs 6 O, but also needs 4 Fe).
  4. 4
    Update Fe: 4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3. Check: Fe: 4 = 4 ✓, O: 6 = 6 ✓.

Answer

4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3
Balancing equations ensures that the same number of each type of atom appears on both sides, satisfying the law of conservation of mass.

Example 2

medium
Balance: \text{C}_3\text{H}_8 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

medium
Balance: \text{Al} + \text{HCl} \rightarrow \text{AlCl}_3 + \text{H}_2.

Example 2

medium
Balance the equation for the formation of ammonia: \text{N}_2 + \text{H}_2 \rightarrow \text{NH}_3.
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Background Knowledge

These ideas may be useful before you work through the harder examples.

chemical equation