1. Topic: Stoichiometry: Balancing Chemical Equations Do Now:

2. What is stoichiometry?
The study of quantitative relationships in a balanced chemical equation
Balance equations represent chemical reactions
Remember in chemical reactions 3 things are conserved
Matter
Energy
charge

3. Law of Conservation of Matter
Matter is neither created nor destroyed
in a chemical reaction
Mass reactants = Mass products
Chemical bonds in reactants may break
New bonds may form to produce products
Number of atoms of each element is “constant”
# of atoms of each element is the same on both sides of the equation

4. Writing Chemical Equations
Begin with word equation
Solid Tin (IV) Oxide is heated with Hydrogen gas to form tin metal and water vapor.
Next go to skeleton equation: replace names of substances with chemical formulas
SnO2(s) + H2(g)  Sn(s) + H2O(g)
Balance skeleton equation: # of atoms of each element is the same on both sides of the equation (law of conversation of mass)
- let’s figure out how to balance

5. Equation Balancing… let’s RAP R A P SnO2(s) + H2(g)  Sn(s) + H2O(g)
1 -
- 1
2 -
- 1
2 -
- 2
NOT BALANCED

6. SnO2(s) + H2(g)  Sn(s) + H2O(g)
1 -
- 1
2 -
- 1 2 4
2 -
- 2 4
Find the most complex compound and then compare the number of each element on product side and reactant side
Look at H2O – 2 Hydrogen and 1 oxygen
On reactant side, 2 Oxygen and 2 Hydrogen
Use Coefficients to balance the numbers of each atom, check number of atoms as you go: NOTE: NEVER CHANGE SUBSCRIPTS
BALANCED 

7. 2SnO2(s) + 4H2(g)  2Sn(s) + 4H2O(g)
NOTE: Coefficients must be in lowest possible ratios
2SnO2(s) H2(g)  2Sn(s) H2O(g)

8. Fe + O2  Fe2O3 4Fe + 3O2  2 Fe2O3 HINTS: Most Complex = Fe2O3
ODDS ARE AKWARD, so Try to make O3 even!!!!!!!
4Fe + 3O2  2 Fe2O3

9. AgNO3 + MgCl2  Mg(NO3)2 + AgCl
HINTS:
Keep polyatomics together
NO3 Ag Cl Mg
2 AgNO3 + MgCl2  Mg(NO3) AgCl

10. Na + H2O  NaOH + H2 HINTS: 2 Na + 2 H2O  2 NaOH + H2
ODDS ARE AKWARD – try to make even
H on product side H + H2 = 3 hydrogens
2 Na H2O  2 NaOH + H2