1. 11.1 Describing Chemical Reactions

2. Chemical Reactions?!

3. Word Equations Reactant(s)  Product(s)
Arrow is read as yields, gives, or reacts to produce
Example: iron + oxygen  iron (III) oxide

4. Chemical Equations
Write the formulas of the reactants to the left of the arrow, products to the right.
Example: Fe(s) + O2(g)  Fe2O3(s)
(s) = solid, (l) = liquid (g) = gas, (aq) = aqueous
Catalyst = speeds up rxn. (written above the arrow)

5. Balancing Chemical Equations
Shows how much of each reactant you need and product you will get.
Coefficients = #s in front of formulas
***both sides of the equation need to have the same # of each atom of each element (Law of Conservation of Mass)
C(s) + O2(g)  CO2(g)

6. Balance THIS H2(g) + O2(g)  H2O(l) 2H2(g) + O2(g)  2H2O(l)
AgNO3 + H2S  Ag2S + HNO3
2AgNO3 + H2S  Ag2S + 2HNO3
Trouble? See page 327 for a list of rules to follow

7. Note…
Need smallest whole-number ratio
Example: 8Al + 6O2  4Al2O3
Simplify: 4Al + 3O2  2Al2O3

8. HINTS…
ALWAYS do oxygen LAST
Watch out: H2O = HOH