New
New
Year 11
OCR
Higher

Burning hydrocarbons

I can write balanced symbol equations for combustion reactions, and describe the difference between complete and incomplete combustion.

New
New
Year 11
OCR
Higher

Burning hydrocarbons

I can write balanced symbol equations for combustion reactions, and describe the difference between complete and incomplete combustion.

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Lesson details

Key learning points

  1. Combustion is the chemical combination of a substance with oxygen, involving the production of heat and light.
  2. Complete combustion of fuels (like hydrocarbons) involve the production of carbon dioxide and water.
  3. The chemical test for oxygen is a combustion reaction, involving relighting a glowing splint.
  4. Incomplete combustion produces carbon particulates (soot) and carbon monoxide due to reduced oxygen levels.

Common misconception

All combustion is complete, producing only CO₂ and water.

Highlight the differences between complete and incomplete combustion.

Keywords

  • Combustion - Combustion is an exothermic reaction where a substance reacts with oxygen.

  • Complete combustion - The complete combustion of fuels, such as hydrocarbons, occurs when enough oxygen is present to convert all the fuel into carbon dioxide and water.

  • Hydrocarbons - Hydrocarbons are compounds containing only hydrogen and carbon atoms.

  • Incomplete combustion - Incomplete combustion is when a substance reacts only partially with oxygen, such as when carbon burns in air, producing carbon dioxide, carbon monoxide and soot (unburnt carbon).

Demonstrate the 'whoosh bottle' to show the amount of energy given out during complete combustion. The products of combustion could be demonstrated by the class teacher.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
When wood burns it reacts with which gas?
carbon dioxide
water vapour
Correct answer: oxygen
nitrogen
Q2.
When a fuel containing carbon is burnt which gas will be produced?
nitrogen
oxygen
argon
Correct answer: carbon dioxide
Q3.
What is a chemical test for carbon dioxide?
Correct answer: bubble through limewater and it will turn cloudy
place a glowing splint in the gas and it will relight
white anhydrous copper sulfate crystals will turn blue
Q4.
What is the scientific name for burning?
respiration
photosynthesis
Correct answer: combustion
precipitation
Q5.
Which of the following are examples of fossil fuels?
Correct answer: crude oil
nuclear fuel
Correct answer: natural gas
Correct answer: coal
Q6.
Match the scientific key terms with the correct definition
Correct Answer:hydrocarbons,molecules made of hydrogen and carbon atoms only

molecules made of hydrogen and carbon atoms only

Correct Answer:conservation of mass,the total mass of reactants equals the total mass of products formed

the total mass of reactants equals the total mass of products formed

Correct Answer:exothermic reactions,chemical reactions in which thermal energy is given out

chemical reactions in which thermal energy is given out

Correct Answer:fossil fuels,fuels made over millions of years from dead plants and animals

fuels made over millions of years from dead plants and animals

6 Questions

Q1.
What word is used to describe the chemical combination of a substance with oxygen involving the production of heat and light?
Correct Answer: combustion, complete combustion, incomplete combustion
Q2.
What are possible products for the complete combustion of methane (a hydrocarbon)?
Correct answer: carbon dioxide + water
carbon monoxide + water
carbon + water
methane + oxygen
carbon dioxide + hydrogen
Q3.
What are possible products for the incomplete combustion of butane (a hydrocarbon)?
carbon dioxide + water
Correct answer: carbon monoxide + water
Correct answer: carbon + water
butane + oxygen
carbon dioxide + hydrogen
Q4.
The chemical test for which gas is to relight a glowing splint?
Correct Answer: oxygen
Q5.
True or false? Complete combustion releases larger amounts of energy than incomplete combustion of the same fuel.
Correct answer: True
False
Q6.
Which of the following shows a correctly balanced equation for the complete combustion of propene (C₃H₆)?
2C₃H₆ + 9O₂ → CO₂ + 6H₂O
2C₃H₆ + O₂ → 6CO₂ + 6H₂O
2C3H6 + 9O₂ → 6CO2 + 6H2O
Correct answer: 2C₃H₆ + 9O₂ → 6CO₂ + 6H₂O