1. Classes of Reaction Equations

2. There are five general classes of reaction equations
Synthesis
Decomposition
Single displacement
Double displacement
Combustion

3. Reaction Equations Each reaction type has a basic formula.
We will use letters to represent the atoms in the general formulas.
A specific and real example will be presented last.

4. Synthesis Basically you have two reactants, but only one product.
General Equation is:
A + B  AB
Examples:
H2 + O2 -> H2O
Mg + O2 -> MgO

5. Decomposition General equation is: AB  A + B
It starts with one reactant and ends up with two or more products.
General equation is:
AB  A + B
Example: H2O2 -> H2O + O2

6. Single Displacement/Replacement
The reaction starts with one element and one compound.
The reaction ends up with a different element and a different compound.

7. Single Displacement/Replacement
Generally:
A + BC  AC + B (cation exchange) or
A + BC  BA + C (anion exchange)

8. Single Displacement/Replacement
Example:
CuCl2 + Al -> AlCl3 + Cu

9. Double Displacement/Replacement
The equation starts with two compounds and ends with two new compounds.

10. Double Displacement/replacement
General equation:
AB + CD - AD + CB
Notice: cations stay cations
Example:
AgNO3 + NaCl -> AgCl + NaNO3

11. Combustion
A hydrocarbon burns with oxygen to form carbon dioxide and water.
A hydrocarbon is hydrogen and carbon containing compounds.

12. Combustion General equation: Hydrocarbon + O2 CO2+H2O Example:
CH3CH3 + O2 -> CO2 + H2O