How to Balance Chemical Equations

1. How to Balance Chemical Equations It is easier than you think.

2. Two Important principles to Remember: #1 - Every chemical compound has a formula which cannot be altered #2 - Every reaction must account for every atom used - The Law of Conservation of Matter

3. What is the Law of Conservation of Matter? VERY Important! • Nothing is created or destroyed but can be changed (rearranged, shuffled about, mixed up, etc..) • The elements you start with … • … are the elements you will finish with, just changed! Methane gas burning The number of atoms of the reactants HAS to equal the products!

4. Balancing Chemical Equations Nomenclature • Subscripts are small numbers to the bottom-right of an element symbol indicating how many atoms of that element are in that molecule. (Circled in blue.) • Coefficients are numbers that go in front of molecules to indicate how many molecules there are. (Boxed in red.)

5. Rules for Balancing Chemical Equations • The number of atoms of the reactants HAS to equal the products! • You can change the number of atoms/molecules by adding Coefficients • Every chemical compound has a formula which cannot be altered • NEVER EVER change the subscripts! • If the subscript changes, the substance changes!

6. Steps to Balance Chemical Equations Count out the number of atoms in each element of the Reactant(s)… and then do the same for the Products. Cu + AgNO3 Cu(NO3)2 + Ag Cu = Ag = N = O = 1 Cu = Ag = N = O = 1 1 1 1 2 3 6

7. Steps to Balance Chemical Equations 2. By adding Coefficients to the compounds/elements you will be able to equal the number of reactant’s atoms with the number of product’s atoms. Cu + 2 AgNO3 Cu(NO3)2 + 2 Ag Cu = Ag = N = O = 1 Cu = Ag = N = O = 1 2 2 2 2 6 6

8. Steps to Balance Chemical Equations 3. After the Coefficients have been added & the calculations done the number of atoms on the Reactants side should equal the number of atoms on the Products side. Cu + 2 AgNO3 Cu(NO3)2 + 2 Ag Cu = Ag = N = O = Cu = Ag = N = O = 1 1 2 2 2 2 6 6

9. Lets try another one - write these down in your notes for examples to use later. Fe + Cl2 FeCl3 Fe = Cl = Fe = Cl = 1 1 2 3

10. Balance the Equation 2 Fe + 3 Cl2 2 FeCl3 Fe = Cl = Fe = Cl = 1 2 1 2 2 6 6 3 Balanced!

11. Attempt to Balance the following… • H2 + O2 H2O • Mg + O2 MgO • KClO3 KCl + O2 • Zn + HCl  ZnCl2 + H2 • N2 + H2  NH3 • Here is a challenging one….. • Pb(NO3)2 + AlCl3  PbCl2 + Al(NO3)3

12. Balance these Chemical Equations • H2O  H2 + O2 • NaCl  Na + Cl2 • Cl2 + NaBr  NaCl + Br2 • CaCO3 + HCl  CaCl2 + CO2 + H2O • Here is a really big Challenge! • C4H10 + O2  O2 + CO2 + H2O