1. BALANCING CHEMICAL EQUATIONS

2. According to the Law of Conservation of Matter, atoms cannot be created or destroyed.
Therefore, matter is conserved and atoms can only be re-arranged to form new substances.
The type and amount of atoms cannot change.

3. WRITING CHEMICAL FORMULAS
To Write a Formula:
1. Write the symbols of the substances to be bonded.
2. Indicate the oxidation number of each substance.
3. Determine what multipliers are needed to equalize the charge.
4. Write the multiplier after each substance.
5. Write the positive substance first, the negative one second.
Example: Calcium and Nitrate
1. Calcium - Ca; nitrate = NO3
2. Ca = +2; NO3 = -1
3. Because 2 X -1 = 2, The multiplier for this formula is 2.
4. The subscripts are 1 and 2; Ca, and (NO3)2.
5. Ca (NO3)2 , or calcium nitrate.

4. The equation for the burning of methane gas in oxygen is:
Balancing Equations
The equation for the burning of methane gas in oxygen is:
CH4 + 2 O2 → CO2 + 2 H2O
Subscript
Shows # of atoms
Coefficient
Shows # of molecules

5. No subscript or coefficient is understood to be 1:
Balancing Equations
No subscript or coefficient is understood to be 1:
CH  O2 → CO  H2O =
C1H4 + 2 O2 → C1O2 + 2 H2O1
1 C  C
4 H  H
4 O  O

8. H2 + O H2O
H = H = 2 4
H = H = 2
O = O = 1
H2 + O H2O
O = O = 1 2
2 H2 + O H2O
H = H = 4
O = O = 2

9. H2 + O H2O
H = H = 2
O = O = 1
H2 + O H2O
H = H = 2 4
O = O = 1 2
2 H2 + O H2O
H = H = 4
O = O = 2

10. C + Cl CCl4

11. SO2 + O SO3

12. CuO + C Cu +CO2

13. Fe2O3 + C Fe + CO2

14. Al + Fe2O Al2O3 + Fe

15. Al2O Al + O2