1. Chemical Equations

2. Chemical Equation
Uses symbols and formulas to represent the products and reactants in a chemical reaction
Equation must contain correct formulas of the reactants and the products

3. Word Equation Reactants and products represented by words
Methane + Oxygen → Carbon dioxide + water
“→” is read as yields

4. Formula Equation Formulas are substituted for words
The equation below is the same as the last word equation with formulas instead
CH4 + O2 → CO2 + H2O

5. Phases On Equations
Phases of reactants and products can also be indicated in the equations
(s) – solid
(l) – liquid
(g) – gas
(aq) – aqueous
(↑) – gas product
(↓) – precipitate – solid product

6. Example
HCl(aq) + Zn(s) → ZnCl2(aq) + H2(↑)

7. Law of Conservation of Matter
Must always be satisfied in chemical reactions
Number of each type of atom must be the same on both sides of the equation
Atoms are neither created nor destroyed

8. Balancing
Making the number of each type of atom the same on both sides of an equation
Coefficient – whole numbers placed in front of the formulas
You can only change coefficients when balancing – you can never change subscripts

9. Balance The Following
CH4 + O2 → CO2 + H2O
Fe + H2O → Fe3O4 + H2