1. Types of Chemical Reactions (3.2) Combustion Reactions

2. The Fire Triangle
for a combustion reaction to occur, 3 things must be present:
Fuel
Oxygen
Heat

3. a hydrocarbon is a compound that is composed only of the elements carbon and hydrogen
ex: methane gas CH4(g)
combustion of a hydrocarbon always produces the compounds, carbon dioxide and water.
ex: CH4(g) O2(g)  CO2(g) H2O(g)

4. Hydrocarbons A general formula for a hydrocarbon is CxHy
Hydrocarbons are often used as fuels
Examples
Name
Formula
methane
CH4(g)
propane
C3H8(g)
butane
C4H10(g)
acetylene
C2H2(g)

5. Combustion Reactions
Combustion of hydrocarbons can be complete or incomplete.
the products depend on the amount of O2 present

6. Complete Combustion occurs when a sufficient amount of O2 is present
all the C atoms and H atoms react to form CO2 and H2O
In general:
hydrocarbon + oxygen  carbon dioxide + water
CxHy + O2(g)  CO2(g) + H2O(g)

7. Incomplete Combustion
occurs if there is not a sufficient amount of O2
ie. fuel is not completely converted into carbon dioxide and water
products include H2O as well as any combination of the following: CO C
CO2
examples:
2 CH4(g) O2(g)  2 CO(g) + 4 H2O(g)
2C3H8(g)+ 7O2(g)  2C(s) + 2CO(g) + 2CO2(g) + 8H2O(g)