1. Additional Science GCSE Chemistry
Balancing Equations
Additional Science GCSE
Chemistry

2. Balancing Equations
A balanced equation must always have an equal number of atoms on each side- atoms can’t just disappear!
You balance the equation by putting numbers in front of the formulas where needed

3. Balancing Equations Ca(OH) + HCL CaCl + H 0
Take this equation for reacting calcium hydroxide with hydrochloric acid:
The formulas are all correct, but the numbers of some atoms don’t match up on both sides. You can’t change a formula like Ca(OH) to Ca(OH)
Ca(OH) + HCL CaCl + H 0 2 2 2 2 3

4. Balancing Equations Only Balance one type of atom at a time!
The more you practise, the quicker you get, but all you do is this:
Find an element that doesn’t balance, and pencil in a number to try and sort it out
See where it gets you. It may create another inbalance, but pencil in anothr number and see where that gets you
Carry on chasing unbalanced elements and it’ll sort itself out pretty quickly

5. Example Ca(OH) + HCL CaCl + H 0 Ca(OH) + HCL CaCl + 2H 0
The only thing you can do about the shortage of H atoms on the left, is make it 2H 0 instead of just H 0 2 2
Ca(OH) + HCL CaCl + H 0 2 2 2
Ca(OH) + HCL CaCl H 0 2 2 2

6. Example Ca(OH) + HCL CaCl + 2H 0 Ca(OH) + 2HCL CaCl + 2H 0
But that now causes too many H atoms on the right hand side, so to balance that up, you could try putting 2HCL in the left side:
And now there it is! Everything balances, and you’ll notice the Cl just sorted itself out. 2 2 2
Ca(OH) HCL CaCl H 0 2 2 2

7. Balance these equations