Combustion Reactions

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Combustion Reactions
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Some Definitions

• Combustion is the rapid reaction of a fuel in
  combination with oxygen.
• Products are usually an oxide and energy.
• Reaction is exothermic.
• Hydrocarbons are molecular compounds made up
  entirely of carbon and hydrogen. They usually
  are produced from fossil fuels.
• Examples
• Methane CH4
• Propane C3H8
• Octane C8H18

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The Combustion Triangle

• In order for combustion to occur, you need
• The amount of oxygen and the fuel will determine
  what kind of combustion you have.

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Complete Combustion

• Only occurs when there is a large supply of
  oxygen.
• Only products are energy, water (H2O), and carbon
  dioxide (CO2).
• Fuels will burn cleanly with no sooty residue.
• Skeleton equation is CXHY O2 ? CO2 H2O
  energy
• Flames are blue in colour.

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Example
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Incomplete Combustion

• Occurs when there is not enough oxygen to convert
  all carbon to carbon dioxide.
• Products are energy, water (H2O), carbon (in the
  form of soot), carbon monoxide (CO) and carbon
  dioxide (CO2).
• Skeleton equation is CXHY O2 ? CO2 H2O CO
  C energy
• Flames are orange and flicker.

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Example
incomplete combustion
complete combustion
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Carbon Monoxide
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Other Combustion Reactions

• Elements will also react with oxygen to form
  oxides.
• General word equation element oxygen ? oxide
  energy
• General skeleton equation A O2 ? AO energy
• Example S8 8O2 ? 8SO2

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Other Combustion Reactions

• Hydrogen Combustion
• 2H2 O2 ? 2H20 energy
• Hydrogen burns cleanly and there is almost an
  endless supply of water.
• Problems
• Hydrogen is highly explosive.
• Making hydrogen from water requires energy.

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Other Combustion Reactions

• Phosphorus Combustion
• P4 5O2 ? P4O10 energy
• Matches are coated in red phosphorus, which is
  relatively unreactive.
• Friction between the striking strip ona match
  box and the red phosphorusproduces heat energy
  which convertsred phosphorus into white
  phosphorus (highly reactive).

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Do Now!

• Complete the following skeleton equations.
  Remember to balance the equations!

• A) __Ca (s) __ O2 (g) ? __ ______ (s) energy
• B) __ C3H8 (g) __ ___ (g) ? __ ___ (g) __ ___
  (g) energy
• C) __ C2H4 (g) __ O2 (g) ? __ ___ (g) __ ___
  energy

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Do Now!

• Complete the following skeleton equations.
  Remember to balance the equations!

• A) 2 Ca (s) 1 O2 (g) ? 2 CaO (s) energy
• B) 1 C3H8 (g) 5 O2 (g) ? 3 CO2 (g) 4 H2O (g)
  energy
• C) 1 C2H4 (g) 3 O2 (g) ? 2 CO2 (g) 2 H2O
  energy

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Homework

• Finish worksheets

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Photo Credits

• http//www.pc.gc.ca/progs/np-pn/eco/eco5.aspx
• http//en.wikipedia.org/wiki/Fire_triangle
• http//www.sciencelearn.org.nz/Contexts/Fire/Sci-M
  edia/Images/Burning-showing-complete-combustion
• http//blogs.triplealearning.com/2011/03/diploma/d
  p_chemistry/combustion-kept-simple/
• http//uvahealth.com/services/plastic-surgery/cond
  itions-treatments/11982
• http//en.wikipedia.org/wiki/FileIgnition_of_a_ma
  tch.jpg