1. Warm Up: Write the skeletal equation for the following word equation:
Solid Lithium reacts with oxygen gas to form solid Lithium Oxide.

2. Balancing Reactions
Learning Target: To be able to balance reactions, using the Law of Conservation of Mass.

3. WARNING
NEVER CHANGE THE SUBSCRIPTS OF THE SUBSTANCES TO BALANCE AN EQUATION!!!!!!!

4. Step 1: How to Balance: Na (s) + Cl2 (g) NaCl (s)
*Count up the atoms of each element on each side of the equation.
Reactant Side Product Side
Na:
Cl:
* If it is a polyatomic ion, and the same polyatomic is on both sides of the equation treat it as a WHOLE UNIT, but if it is not the same on both sides you MUST separate it into each individual element.

5. Step 2: How to Balance Na + Cl2 NaCl ___Na(s) + ___Cl2(g) ⇒ ___NaCl(s)
Reactant Side Product Side
Na:
Cl:
___Na(s) + ___Cl2(g) ⇒ ___NaCl(s)
*Place coefficient(s) in front of a substance/substances until they are equal amounts of each element/ion on each side.
*Reduce coefficients if necessary.

6. Practice: ___Na3N(s) ⇒ ___N2(g) + ___Na(s)
Lithium reacts with water to form lithium oxide and hydrogen
___Cu(s) + ___AgNO3(aq) ⇒ ___Ag(s) + ___Cu(NO3)2
(Count Nitrate as one item instead of nitrogen and oxygen atoms)

7. Balancing Combustion Rxn:
These reactions are harder to balance… But there is a TRICK!!!
____C2H6(g) + ____O2(g) → ____H2O(g) + ____CO2(g)
Take the subscript of Carbon (on the reactant side) and make it the coefficient for carbon dioxide (on the product side)
Divide hydrogen’s subscript (on the reactant side) in half and it becomes water’s coefficient (on the product side)
If you put an odd number in front of H2O then double all your coefficients, except for O2. If you put an even number in front of H2O then skip this step.
Count up the number of oxygen on the product side, then divide it by 2, and that is oxygen’s coefficient (on the reactant side).

8. Practice Combustion Rxn:
____C3H8(g) + ____O2(g) → ____CO2(g) + ____H2O(g) ____C5H12(g) + ____O2(g) → ____CO2(g) + ____H2O(g) ____C4H10(g) + ____O2(g) → ____CO2(g) + ____H2O(g)

9. A few more….
____HCl(aq) + ____CaCO3(s) → ____H2CO3(aq) + ____CaCl2(aq) Nickel (III) Oxide decomposes into Nickel and Oxygen ____KCl(aq) + ____AgNO3(aq) → ____AgCl(s) + ____KNO3(aq) Iron metal reacts with water to form iron (III) oxide and hydrogen ____NO2 + ____O2 → ____N2O5