1. Lecciòn 1
Recognizing Four Types of
Chemical Reactions St. Anne`
School

2. Today we shall look at four types of chemical
reactions ……
1.Synthesis
2.Decomposition
3.Singlereplacement
4.Double replacement

3.  A chemical reaction takes place when two or
more substances combine and yield one or more
other substances with different characteristics.

4. Today we shall look at four types of chemical
reactions ……
1.Synthesis
2.Decomposition
3.Singlereplacement
4.Double replacement

5. Today we shall look at four types of chemical
reactions ……
1.Synthesis
2.Decomposition
3.Singlereplacement
4.Double replacement

6. Synthesis occurs when two substances combine
chemically to yield a new substance with
different properties.
For example
Sodium plus Chlorine yield Salt
Na + Cl  NaCl

7. Decomposition takes place when a substance is
broken down into two or more substances with
different properties.
For example
2H2O  O2 + 4H
Water yields Oxygen and Hydrogen

8. Single replacement takes place when a substance
takes the place of another substance in a
compound.
For example
2Al + 3Ag2 S  3Ag + Al2S3
Aluminum plus Silver sulfide yields Silver plus Aluminum
sulfide

9. Double Replacement takes place when substances
exchange places.
For example
NaOH + H2SO4  Na2SO4 + H2O
Sodium hydroxide and Sulfuric acid yield Sodium sulfate and water

10. See if you can tell what the following type of
Reaction is
4Fe + 3O2  2Fe2O3