What are the steps to balancing chemical equations?

1) 2Mg + O2 -------> 2MgO

2) 4Na + O2 ------> 2Na2O

3) Its balanced.


both sides have to have the same number of molecules.

1) Mg + O2 ? MgO
By looking at the equation, you can see that the right side has less oxygen atoms. In order to fix this, we double the amount of MgO on the right.
Mg + O2 ? 2MgO

However, you'll quickly notice that the left side now has less Magnesium atoms. To fix this, we double it to give:
2Mg + O2 ? 2MgO

Now there is an equal number of each atom on both sides (2 Mg and 2 O)
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2) Na + O2 ? Na2O
There are twice as many O on the right as there are on the right. To fix this, we multiply the coefficient of Na2O by 2 to give:
Na + O2 ? 2Na2O

However, there are now 4 times as many Na on the left.To fix this...:
4Na + O2 ? 2Na2O
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3) Sn + Cl2 ? SnCl2
The number of each atom on both sides is the same, so the equation is already balanced.