1. Unit 3: Chemical Equations and Stoichiometry
Balancing Equations

2. Balancing Equations reactants  products
Remember the law of conservation of mass?
When a chemical reaction occurs, no atoms are created or just destroyed – they are just rearranged
amount of each element on the left side (reactants) must equal the amount of the same element on the right side (products)
reactants  products

3. Balancing Equations – The Steps!
Put coefficients in front of each substance to get the quantities on the left side = the right side
2Na + Cl2  2NaCl
Use the smallest whole number coefficients possible.

4. Balancing Equations - Hints
Save oxygen for last
Save hydrogen for 2nd to last

5. Balancing Equations Example #1
Now let’s balance this equation…
__C3H8(g) + __O2(g)  __CO2(g) + __H2O(g)

6. Balancing Equations Practice #1
Balance the following chemical equation:
__PbS2 + __O2  __PbO2 + __SO2