1. Chemical Reactions

2. Types of Reactions
There are five types of chemical reactions we will talk about:
Combination reactions
Decomposition reactions
Single replacement reactions
Double replacement reactions
Combustion reactions
You need to be able to identify the type of reaction and predict the product(s)

3. 1. Combination reactions
Combination reactions occur when two substances (generally elements) combine and form a compound.
reactant + reactant  1 product
Basically: A + B  AB
Example- Water: 2H2 + O2  2H2O

4. Practice
Predict the products. Write and balance the following synthesis reaction equations.
Sodium metal reacts with chlorine gas
2Na+ Cl2  2NaCl
Solid Magnesium reacts with fluorine gas
Mg + F2  MgF2

5. 2. Decomposition Reactions
Decomposition reactions occur when a compound breaks up into elements or simpler compounds. ( think reverse of combination )
1 Reactant  Product + Product
In general: AB  A + B
Example: 2 H2O  2H2 + O2

6. 3. Single Replacement Reactions
Single Replacement Reactions occur when one element replaces another in a compound.
A + BC  AC + B

7. Single Replacement Reactions
Example:
Magnesium metal reacts with hydrochloric acid
Mg HCl  MgCl2 + H2
Note: Magnesium replaces the hydrogen ion in the reaction

8. 4. Double Replacement Reactions
Double Replacement Reactions occur when a metal replaces a metal in a compound and a nonmetal replaces a nonmetal in a compound
AB + CD  AD + CB

9. Double Replacement Reactions
Think about as first and last ions go together and the inside ions go together
Na will go with Cl
S will go with H

10. 5. Combustion Reactions Hydrocarbon
Combustion reactions occur when a hydrocarbon (CxHy)reacts with oxygen gas (O2).
This is also called burning!!! In order to burn something you need the 3 things in the “fire triangle”:
Hydrocarbon

11. Combustion Reactions In general: CxHy + O2  CO2 + H2O
Note: ALWAYS results in carbon-dioxide and water
Combustion is used to heat homes and run automobiles

12. Combustion
Example:
Methane and Oxygen combust when heated
We capture methane from landfills and burn it to produce electricity.