Types of Reactions: Combustion LG: I can recognize and predict
products of combustion reactions; I can describe hazards of
incomplete combustion
Slide 2
Combustion A combustion reaction occurs when a substance (fuel)
burns in oxygen Typically oxygen is supplied by the air, which is
only ~21% oxygen Chemical energy stored in the bonds of a fuel are
released as heat and light during combustion
Slide 3
Hydrocarbons Many fuels are organic substances called
hydrocarbons; they contain only carbon and hydrogen Examples:
Propane and butane Many fuels contain contaminants such as heavy
metals and sulfur compounds that can result in air pollution when
these fuels are burned
Slide 4
Complete Combustion of Hydrocarbons Occurs when fuels react
with excess oxygen Chemical bonds in the fuel are broken to release
the maximum amount of energy The only products are carbon dioxide
and water: C 4 H 10(g) + O 2(g) CO 2(g) + H 2 O (g)
Slide 5
Incomplete Combustion of Hydrocarbons Occurs when the supply of
oxygen is limited Burning a fuel in an enclosed space (using a BBQ
or running a car engine in the garage Flames from incomplete
combustion contain soot; this is the result of un-reacted carbon
Complete (lots of O 2 ): C 7 H 16(l) + O 2(g) CO 2(g) + H 2 O (g)
Incomplete (low O 2 ): C 7 H 16(l) + O 2(g) CO (g) + H 2 O (g)
Incomplete (very low O 2 ): C 7 H 16(l) + O 2(g) C (s) + CO (g) +
CO 2(g) + H 2 O (g)
Slide 6
Problems with Incomplete Combustion Only releases SOME of the
energy available in a fuel (as a result, the flame is cooler =
yellow/orange); this increases cost of burning fuel Soot particles
are toxic to the respiratory tract Carbon monoxide is a colourless,
odourless, tasteless gas, and is structurally similar to oxygen and
so can attach to our red blood cells200X better than oxygen
Slide 7
Practice Write the balanced equation (with states) for the
complete combustion of liquid octane (C 8 H 18 )