Grade 11 Chemistry
Combustion Reactions
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Hydrocarbons are organic compounds formed entirely of carbon and hydrogen
Alkanes have the general formula CnH2n+2 Alkanes are named based on the number of carbons they
contain.Their names are composed of: a stem followed by the suffix –ane
Name
Methane
Formula
Uses
Structure
CH4
Cooking
Heating
H
H C H
H
Ethane
C2H6
Catalyst
H H
H C C H
H H
Propane
C3H8
Barbecues
H H H
H C C C H
H H H
Butane
C4H10
Lighters
H H H H
H C C C C H
H H H H
Pentane
C5H12
Solvents
H H H H H
H C C C C C H
H H H H H
Hexane
C6H14
Solvents
Glues
H H H H H H
H C C C C C C H
H H H H H H
Heptane
C7H16
Solvents
H H H H H H H
H C C C C C C C H
H H H H H H H
Octane
C8H18
Cars
H H H H H H H H
H C C C C C C C C H
H H H H H H H H
Reference: http://www.nyu.edu/pages/mathmol/library/hydrocarbons/
Diagram
Combustion Of Hydrocarbons
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A combustion reaction occurs when a________________ burns with __________.
Two Types: Complete & Incomplete Combustion
A. Complete
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Occurs when there is excess oxygen
All the carbon compounds turn to carbon dioxide and water
Hydrocarbon combusts (burns) with a clean flame.
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Energy ............................. heat, light
Hydrocarbons ................... compounds containing hydrogen & carbon
Carbon dioxide.................. contributor to the greenhouse effect
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B. Incomplete
 Occurs when there is not enough oxygen
 Hydrocarbon combusts (burns) with a smokey or sooty flame.
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Carbon monoxide .......... .......poisonous
Carbon .............................. black soot
1. Write word equations to represent the complete and incomplete combustion of propane, a fuel used in
stoves and home heating.
2. a) Write balanced chemical equations for the reactions in #1 above, given that the chemical formula of
propane is C3H8.
b) How are complete and incomplete combustion different?
3. Write the balanced chemical reactions for the following:
a) combustion reaction with propane
b) combustion reaction with butane
c) combustion reaction with octane
d) combustion reaction with propane
e) complete combustion of ethanol (C2H5OH)
f) incomplete combustion of acetylene (C2H2)
4. Explain how both complete and incomplete combustion can pose environmental hazards.
5. Why should cars and gas barbeques never be operated in an enclosed space like a garage?