1. Unit: Chemical Reactions Balancing chemical equations Day 2 - Notes

2. After today you will be able to… Explain the Law of Conservation of Atoms Balance equations using the “tally method”

3. Law of Conservation of Atoms: There must be the same number of each type of atom before the reaction as after the reaction.

4. Coefficients: Are numbers that go in front of each substance to indicate the number of atoms or molecules that are reacting or being produced.

5. Let’s try some examples! We will be using the “tally method” to balance equations in this class.

6. Examples: Balance the following equation: ___ Al + ___S  ___Al 2 S 3 Al S 1 1 2 3 2 2 3 3 If the numbers match on either side… You’re balanced!

7. Examples: Balance the following equation: ___ Li + ___O 2  ___Li 2 O Li O 1 2 2 1 2 2 2 2 4 4 4

8. Examples: Balance the following equation: ___Fe 2 (SO 4 ) 3 + ___Na 3 (PO 4 )  ___Fe(PO 4 ) + ___Na 2 (SO 4 ) Fe (SO 4 ) 2 3 2 2 Na (PO 4 ) 3 3 1 1 1 2 1 2 2 3 6 2 6 Are we balanced? YES!!!! Helpful tip: Do not separate polyatomic ions!

9. Do now: Complete “Exit Ticket” Then: Begin WS 2 (Homework)