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Lesson 2.4: Combustion Reactions
In some areas of the Arctic, large amounts of methane, CH4 (g) are entering the
atmosphere.
Where is it coming from?
As the climate becomes warmer and the ground thaws bacteria produce
methane from the remains of dead plants and animals.
How do scientists find the methane in the arctic?
Digging a hole and igniting the gas (easier done over a lake).
Methane is a hydrocarbon, a compound that is composed only of the elements
carbon and hydrogen.
The combustion of hydrocarbons can be either complete or incomplete.
Complete Combustion
Methane:
CH4 (g) + 2O2 (g) →
CO2 (g) + 2H2O(g)
General Hydrocarbon:
CxHy + 2O2 (g) → CO2 (g) + 2H2O(g)
Hydrocarbons and their uses:
Incomplete Combustion
To have the complete combustion, the correct amount of oxygen is required. If
there is too little oxygen, then incomplete combustion occurs.
Incomplete combustion of propane:
2C3H8 (g) + 7O2 (g) → 2C(s) + 2CO(g)+ 2CO2 (g) + 8H2O(g)
What is the product in this reaction that can cause deposits of a dark substance to
form on nearby surfaces?
Soot: fine particles consisting mostly of carbon
Ex #1: What is the balanced chemical equation for the complete combustion of
butane?
2C4H10 (g) + 13O2 (g) → 8CO2 (g) + 10H2O(g)
Ex. #2: Write a balanced chemical equation for the incomplete
combustion of hexane, C6H14 (l).
C6H14 (g) + 5O2 (g) → 4C(s) + CO(g)+ CO2 (g) + 7H2O(g)
EX #3: Write the combustion reaction of glucose.
C6H1206 (g) + 6O2 (g) → 6CO2 (g) + 6H2O(g)