Balancing equations- Key Steps!

 

  1. List out the different atoms in the formula.
  2. Count the number of atoms on the left hand side, then on the right hand side.
  3. Note which atoms are not balanced.
  4. Select on atom to balance (it is usually the one that is an odd number). You can only balance by putting numbers in front of the elements!
  5. Update the atom count.
  6. If it is still unbalanced, you may need to try balancing the elements again.

 

Example

 

Al + O2 Al2O3

                                                                                                                                                                                                                  

 

Atom

Number of Atoms

Al

1

O

2

Atom

Number of Atoms

Al

2

O

3

 

 

 

 

 

Oxygen is unbalanced!

 

Al + O2 2Al2O3

Atom

Number of Atoms

Al

1

O

2

Atom

Number of Atoms

Al

4

O

6

 

 

 

 

 

 

 

Now Aluminium and Oxygen are unbalanced, but we can change the left hand side of the equation to balance both sides.

 

 

4Al + 3O2 2Al2O3

Atom

Number of Atoms

Al

4

O

6

Atom

Number of Atoms

Al

4

O

6

 

 

 

 

 

 

Now both sides are balanced!

Useful books for revision:

Revise AS Chemistry for Salters (Written by experienced examiners and teachers of Salter's chemistry)
Revise AS Chemistry for Salters (OCR) (Salters Advanced Chemistry)

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