The full lesson can be viewed by enrolling in the Year 10 Chemistry Online Course or by purchasing the Year 10 Chemistry Lesson Notes.

Learning Objective

In this lesson we will revise how to balance a chemical equation to reflect the conservation of mass during a chemical reaction.

Learning Outcomes

By the end of this lesson you will be able to:

- Write word equations and formula equations to represent chemical reactions.

- Include states of matter in formula equations.

- Balance formula equations to reflect conservation of mass.

## Lesson Summary

- A word equation shows the chemical names of all reactants and products involved in a chemical reaction.

- A formula equation shows the chemical formulas of reactants and products.

- Formula equations may also include the states of matter of reactants and products, in brackets after each chemical formula.

- (s) represents solids.

- (l) represents liquids.

- (g) represents gases.

- (aq) represents aqueous solutions.

- A balanced equation shows the ratios of reactants and products.

- A balanced equation reflects the Law of Conservation of Mass and shows that atoms are neither created nor destroyed during a chemical reaction, but only rearranged.

- Steps for balancing a chemical equation:

- Write the formula equation showing all reactants and products.

- Tally up the total numbers of each type of atom for both sides of the equation.

- Place coefficients in front of reactants and products until there are equal numbers of each type of atom on both sides of the equation.

(Header image: JSquish, Wikimedia Commons)