1. Balancing Equations

2. Law of Conservation of Mass
The Law of Conservation of Mass states: that mass is neither created nor destroyed in any chemical reaction. Therefore balancing equations requires the same number of atoms on both sides of a chemical reaction.
The number of atoms in the Reactants must equal the Number of atoms in the Products

3. Balance elements in the following order:
Nonmetals
Metals
Polyatomic ions
Hydrogen
Oxygen

4. Polyatomic Ions
When balancing polyatomic ions treat them as one unit if they appear on both sides of the equation.

5. Balancing Equations N2 + H2 NH3 __N__ 2 1 __H__ 2 3
Complete an atom inventory.
2 1
2 3
__N__
__H__

6. Balancing Equations N2 + H2 2NH3 Nothing is balanced.
Balance the nitrogen first by placing a coefficient of 2 in front of the NH3.
N2 + H NH3

7. Balancing Equations N2 + 3H2 2NH3 2 2 6 6 __N__ __H__
Hydrogen is not balanced.
Place a 3 in front of H2.
N H NH3
Complete a final atom inventory.
2 2
6 6
__N__
__H__

8. Balancing Equations C3H8 + O2→ CO2+ H2O __C__ 3 1 __H__ 8 2 __O__ 2 3
Complete an atom inventory.
3 1
8 2
2 3
__C__
__H__
__O__

9. Balancing Equations C3H8 + O2 → 3CO2+ H2O Nothing is balanced.
Balance the carbon first by placing a coefficient of 3 in front of the CO2.
C3H O2 → 3CO2+ H2O

10. Balancing Equations C3H8 + O2 → 3CO2+ 4H2O
Now balance the hydrogen by placing a 4 in front of the water on the products side.
C3H O2 → 3CO2+ 4H2O

11. Balancing Equations C3H8 + 5O2 → 3CO2+ 4H2O __C__ 3 3 __H__ 8 8 __O__
Balance the oxygen on the reactants side with a coefficient of 5.
C3H8 + 5O2 → 3CO2+ 4H2O
Complete a final atom inventory.
3 3
8 8
__C__
__H__
__O__

12. Balancing Equations BF3+ Li2SO3→ B2(SO3)3+ LiF 1 2 3 1 2 1 1 3 __B__
Complete an atom inventory.
1 2
3 1
2 1
1 3
__B__
__F__
__Li__
__SO3__

13. Balancing Equations BF3+ Li2SO3→ B2(SO3)3+ 3LiF Nothing is balanced.
Balance the fluorine first by placing a coefficient of 3 in front of the LiF.
BF3+ Li2SO3→ B2(SO3)3+ 3LiF

14. Balancing Equations 2BF3+ Li2SO3→ B2(SO3)3+ 3LiF
Now balance the boron by placing a 2 in front of the BF3 on the reactants side.
2BF3+ Li2SO3→ B2(SO3)3+ 3LiF
Notice we’ve unbalanced the fluorine, and now must adjust our coefficients.

15. Balancing Equations 2BF3+ Li2SO3→ B2(SO3)3+ 6LiF
Now balance the boron by placing a 2 in front of the BF3 on the reactants side.
2BF3+ Li2SO3→ B2(SO3)3+ 6LiF
Notice we’ve unbalanced the fluorine, and now must adjust our coefficients.

16. Balancing Equations __B__ 2BF3+ 3Li2SO3→ B2(SO3)3+ 6LiF 2 2 __F__ 6 6
Balance the lithium sulfite on the reactants side with a coefficient of 3.
2BF3+ 3Li2SO3→ B2(SO3)3+ 6LiF
Complete a final atom inventory.
__B__
__F__
__Li__
__SO3__
2 2
6 6

17. YOU ARE BALANCED!!