Balancing Equations

What is Balancing Equations?

Within Chemistry, which covers atoms, bonding, reactions, the periodic table, organic chemistry and the chemistry of everyday life, this topic explains Balancing Equations. Chemistry links what you can see in the lab to the particles and bonds behind it, so each topic here shows that link in a model.

Check that you can explain Balancing Equations in your own words and give one example from everyday life. If you can do that, you have understood the core idea.

Understanding Balancing Equations helps you explain why substances behave as they do, from cleaning products and food to medicines.

Balancing Equations in detail

A balanced equation has the same number of each type of atom on both sides, because atoms are not created or destroyed in a reaction. You balance by writing numbers in front of formulae, called coefficients, and never by changing the subscripts in formulae.

Start with the most complex compound, balance elements that appear in one substance on each side first, and leave single elements such as O₂ until last. For example, H₂ + O₂ → H₂O balances as 2H₂ + O₂ → 2H₂O. Count atoms carefully on both sides to check.

How the interactive helps you understand Balancing Equations

Click a step, or use the Previous and Next buttons, to move through the sequence one stage at a time. Auto-play moves on for you.

Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Balancing Equations.

Real-life uses and examples

• Explain Balancing Equations in an exam by linking the particles involved to what you observe.
• Use Balancing Equations to explain what happens in a lab experiment and why.
• Link Balancing Equations to everyday products such as cleaning agents, food and medicines.

Common mistakes to avoid

• Mixing up the names of substances or ions when you describe Balancing Equations.
• Describing what happens without explaining the particles or bonds involved.
• Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.