1. Types of Chemical Reactions

2. Thousands of known chemical reactions occur.
We can classify reactions according to various similarities.
General information about types of chemical reactions can be used to predict the products of specific reactions.
We are going to classify reactions according to five basic types

3. Synthesis
Decomposition
Single-displacement
Double-displacement
Combustion

4. Synthesis Reactions A + X  AX
Two or more substances combine to form a new compound

5. Types of Synthesis Reactions
A metal + O2  a metal oxide
A metal + S8  a metal sulfide
A nonmetal + O2  nonmetal oxide
A metal + a halogen  a halide
Active metal oxide + water  metal hydroxide
Nonmetal oxide + water  oxyacid

6. Decomposition Reactions
AX  A + X
A single compound undergoes a reaction that produces two or more simpler substances

7. The decomposition of a substance by running an electric current through it is called electrolysis.
This is how water is decomposed into hydrogen and oxygen gases.

8. Types of Decomposition Reactions
Oxides of less-active metals decompose into their elements
Metal carbonates decompose when heated to produce a metal oxide + CO2
Metal hydroxides decompose when heated to form metal oxide + water
Metal chlorates decompose when heated to form a metal chloride + O2
Some acids decompose into nonmetal oxides + water

9. Single-Displacement Reactions
A + BX  AX + B or Y + BX  BY + X
One element replaces a similar element in a compound.
A metal displaces a metal
A halogen displaces a halogen
A metal can displace hydrogen or vice versa
Often takes place in aqueous solution.

10. Types of Single Displacement Reactions
A metal in a compound can be displaced by another metal
One hydrogen in water can be displaced by an active metal
The hydrogen in an acid can be displaced by an active metal
The halogen in a compound can be displaced by another halogen

11. Single displacement reactions can only take place when the single element is MORE reactive than the element it is replacing in the compound

12. Double Displacement Reactions
AX + BY  AY + BX
The ions of two compounds exchange places in aqueous solution to form two new compounds.
One of the compounds formed is usually a precipitate, an insoluble gas, or a molecular compound (like water).

13. Types of Double-Displacement Reactions
Precipitate Formation
One of the compounds produced is insoluble in water and so precipitates out of the solution
Gas Formation
One of the compounds produced is an insoluble gas that bubbles out of the solution.
Water formation
One of the compounds produced is water
Remember that H+ + OH- = H2O

14. Combustion Reactions A substance combines with oxygen
The reaction produces a large amount of energy in the form of light and heat
The combustion of hydrocarbons produces CO2 and H2O
CxHy + O2  CO2 + H2O