L03. Burning hydrocarbons

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L03. Burning hydrocarbons
Lesson Outcomes APP AF1, AF2, AF3, AF4 HSW 1a, 2c How I did Targets
Task 1 Describe what happens when hydrocarbon fuels burn, and how the products of combustion can be identified. Grade C
Task 2 Explain the advantages of complete combustion and link this to the choice of fuels. The problems associated with incomplete combustion Grade B
Task 3 Write balanced symbol equations for complete, and incomplete, combustion Grade A/A

• Connector (Grade D)
• Answer in full sentences
• What is a fuel?
• Name three fuels.
• What do you consider
• to be the most important
• properties of a fuel?
• What is the scientific word
• for when a fuel burns?

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• A fuel is a substance that contains stored
  chemical energy.
• When fuels are burned in the air (with oxygen)
  they release heat and light energy.
• petrol, wood, ethanol, coal, macaroni, sugar,
  etc.
• A good fuel would release a lot of heat energy
  with little or no polluting or harmful
  by-products.
• Combustion

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BIG picture

• What skills will you be developing this lesson?
• ICT
• Numeracy
• Literacy
• Team work
• Self management
• Creative thinking
• Independent enquiry
• Participation
• Reflection
• How is this lesson relevant to every day life?
  (WRL/CIT)

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Task 1 (Grade C)

• Task 1
• Describe what happens when hydrocarbon fuels
  burn, and how the products of combustion can be
  identified.

Keywords for Task 1 Combustion, Complete
combustion Fuel
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Combustion
Compounds containing H and C are called?
fuel
Many fuels like coal, oil, petrol, candle wax,
and natural gas are called HYDROCARBONS
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The products of burning a hydrocarbon
to pump
water and ice
water and ice
limewater
anhydrous cobalt chloride paper
Hydrocarbons are compounds of carbon and hydrogen
ONLY. When pure carbon is burned, carbon dioxide
is formed and when hydrogen is burned, water is
produced.

1. What happens to the anhydrous cobalt chloride
   paper?
2. What happens to the limewater?
3. Explain the significance of the above
   observations.

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Task 1 Review
Go back to your lesson outcome grid and fill out
the How I did and the Targets column.
Lesson Outcomes How I did Targets
Task 1 Describe what happens when hydrocarbon fuels burn, and how the products of combustion can be identified. Grade C Met? Partly met? Not met? How can I improve on task 1?
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Task 2 (Grade B)

• Task 2
• Explain
• the advantages of complete combustion and link
  this to the choice of fuels.
• The problems associated with incomplete
  combustion
• Task 2 Extension

• Keywords for Task 2
• Combustion,
• Complete combustion,
• Fuel
• Carbon monoxide,
• Incomplete combustion,
• Pollution,
• Soot,
• Toxicity

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What makes a good fuel?
From the pictures below, choose the best fuel.
Explain your choice.
Yellow flame, soot
Blue flame, no soot
Yellow flame, soot, ash (residue)
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Summary exercise

• Fuels contain stored __________ . When fuels burn
  they react with __________ in the air and give
  out __________ energy. This is called a
  __________ reaction. Most fuels contain carbon
  and __________ atoms. When the fuel burns these
  atoms react with oxygen to make __________
  dioxide and __________ .

energy
oxygen
heat
combustion
hydrogen
carbon
water
carbon combustion energy heat hydrogen
oxygen water
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Complete and incomplete combustion
Lots of oxygen
Methane
This is called Complete combustion
Some oxygen
Methane
Oxygen

This is called Incomplete combustion
Little oxygen
Methane
This is also called Incomplete combustion
To get complete combustion the fuel must be
burned in EXCESS O2.
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The hazard of incomplete combustion
Why did the man die?
Less amount of available oxygen caused the
release of colourless, odourless, poisonous
carbon monoxide.
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Incomplete combustion
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Carbon monoxide
Edexcel video
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Question
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Homework

• Homework task
• Due date
• Criteria for Grade C
• Criteria for Grade B

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Summary

• When a fuel burns with a good supply of
  __________ to form carbon dioxide and water it is
  called __________ combustion. When a fuel burns
  without a good enough supply of oxygen and forms
  deadly carbon __________ (and/or soot) and water
  it is called __________ combustion. Incomplete
  combustion can happen in faulty gas boilers if
  their air __________ vent is blocked. Carbon
  monoxide is a __________ , __________ , toxic
  gas. It kills because it stops your blood from
  carrying __________ .

oxygen
complete
monoxide
incomplete
intake
odourless
colourless
oxygen
colourless complete incomplete
intake monoxide odourless oxygen oxygen
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Task 2 Review
Go back to your lesson outcome grid and fill out
the How I did and the Targets column.
Lesson Outcomes How I did Targets
Task 2 Explain the advantages of complete combustion and link this to the choice of fuels. The problems associated with incomplete combustion Grade B Met? Partly met? Not met? How can I improve on task 2?
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Task 3 (Grade A/A)

• Task 3
• Write balanced symbol equations for complete,
  and incomplete, combustion
• Task 3 Extension

• Keywords for Task 3
• incomplete combustion
• complete combustion

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Combustion of methane

• Write the word equation for combustion of
  methane.
• Write a balanced symbol equation for the
  combustion of
• methane.

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Write the balanced symbol equations for these
reactions

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Extension task

• Some camping gas stoves run on propane gas.
  Propane molecules have the formula C3H8.
• (a) What new chemicals are produced when you burn
  propane?
• (b) Write a word equation for the combustion
  reaction of propane.
• (c) Write a balanced formula equation for this
  reaction. (Hint you will need five oxygen
  molecules for every propane molecule.)

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Task 3 Review
Go back to your lesson outcome grid and fill out
the How I did and the Targets column.
Lesson Outcomes How I did Targets
Task 3 Write balanced symbol equations for complete, and incomplete, combustion Grade A/A Met? Partly met? Not met? How can I improve on task 3?
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Review of lesson a selection of past paper
questions
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Question
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Can you explain these key words?
Combustion, complete combustion, Fuel Carbon
monoxide, incomplete combustion, pollution, soot,
toxicity
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Technicians list Demonstration 1 Eye
protection Two gas jars of oxygen Deflagrating
spoon Two stoppered boiling tubes of hydrogen Dry
cobalt chloride paper (blue) Forceps Splints Limew
ater (corrosive) Charcoal Demonstration
2 Combustion rig