Year 10 Science · Unit 2 · Lesson 9
Foundation Worksheet
Learning Goals
Order the steps
Number the steps from 1 to 7 to show the correct order for balancing a chemical equation. Step 1 = what you do first.
| Order | Step |
|---|---|
| Add coefficients in front of formulae to balance the equation, never change subscripts. | |
| Count atoms of each element on both sides of the equation. | |
| Write the word equation for the reaction. | |
| Recount atoms on both sides to confirm all elements are balanced. | |
| Replace the words with correct chemical formulae (and state symbols if required). | |
| Identify which elements are not yet balanced. | |
| Check that the total number of each atom is the same on both sides. Write the final balanced equation. |
True or False? Fix the false ones
Circle T or F for each statement. If the statement is false, rewrite it correctly on the line below.
To balance the equation H₂ + O₂ → H₂O, you should change the subscript in water to H₂O₂ so both sides have 2 oxygen atoms.
Correct it:
Both sides of a balanced chemical equation must contain the same total number of atoms of each element.
Correct it:
State symbols such as (s), (l), (g), and (aq) describe the physical state of each substance and must always appear in a balanced equation.
Correct it:
The balanced equation for iron rusting is: 4Fe + 3O₂ → 2Fe₂O₃.
Correct it:
1. Explain why you must NEVER change a subscript in a chemical formula when trying to balance an equation. What does changing a subscript actually do?
2. Balance the following equation by adding coefficients only: H₂ + O₂ → H₂O. Show your atom count before and after balancing.
Wrap Up
In one sentence, what was the main idea of this lesson?