1. Balancing Equations Remember the Law of Conservation of Mass What you start with you have to end up with You can add more of an atom by changing the coefficients 1 is understood DO NOT CHANGE THE SUBSCRIPTS Start with atoms that only appear once in the formula Metals or other rare elements Balance hydrogen and oxygen last

3. Example: 2H2 + O2  2H2O

5. 1 Reactant  Product + Product

6. In general: AB  A + B

7. Example: 2 H2O  2H2 + O2

9. A metal can replace a metal (+) OR a nonmetal can replace a nonmetal (-).

10. element + compound product + productA + BC  AC + B (if A is a metal) OR A + BC  BA + C (if A is a nonmetal) (remember the cation always goes first!)

13. Compound + compound  product + product

19. Products in combustion are ALWAYS carbon dioxide and water. (although incomplete burning does cause some by-products like carbon monoxide)

21. C5H12 + O2 CO2 + H2O

22. Write the products and balance the following combustion reaction: