Lesson Plan

4. Outline the combustion reaction

KS3-14-04

Intent

Learning Intention

  • Understand the concept of combustion; define combustion and identify when a chemical reaction involves combustion
  • Learn about the products of combustion; identify the products of combustion, including carbon dioxide, water, and other gases
  • Develop problem-solving skills related to combustion; apply knowledge of combustion to solve problems related to chemical reactions involving combustion

National Curriculum

  • Learn about combustion and understand the conditions needed for combustion to occur
  • Learn that some reactions, such as oxidation, combustion, oxidation, and thermal decomposition, are exothermic and others, such as those with acids, are endothermic
  • Understand that reactions may occur at different rates and that temperature, concentration, pressure of reacting gases, surface area, and the presence of catalysts may affect reaction rates

Working Scientifically

  • Select, plan and carry out the most appropriate types of scientific enquiry to test predictions, including identifying independent, dependent and control variables. 
  • Use appropriate techniques, apparatus, and materials during fieldwork and laboratory work, paying attention to health and safety

Learning Outcomes

  • Understand the difference between complete and incomplete combustion
  • Understand the environmental implications of incomplete combustion
  • Compare combustion of fuels through a practical activity

Resources

Resources: matches, boiling tube, tongs, thermometer, stopwatch, measuring cylinder, 2dp mass balance, water, the handout and fuel samples. 

Core Handout: A sheet to accompany the Mission Assignment. The second handout contains a template for the students to complete their combustion report. 

Rocket words

  • combustion
  • extinguish
  • fuel
  • complete combustion
  • incomplete combustion

Implementation

Prior Learning 

From KS2, the students may be familiar with combustion as the chemical reaction between a fuel source and oxygen, resulting in the release of energy and the formation of products such as water and carbon dioxide.

Starter

Begin the lesson by asking students to recall what combustion is and what are the products of combustion. Then, show the students a picture of a candle and ask them what they think is happening when the candle burns. Finally, introduce the concept of complete and incomplete combustion.

Main Teaching

  1. Demonstrate the difference between complete and incomplete combustion using a Bunsen burner (optional).
  2. Firstly, demonstrate complete combustion by burning a small piece of paper with a blue flame.
  3. Then, demonstrate incomplete combustion by using the Bunsen burner with the air hole partially closed. This should result in a yellow flame and the production of soot.
  4. Ask students to work in pairs to identify the products of complete and incomplete combustion using a worksheet.
  5. Discuss the results as a class, emphasising the importance of identifying and understanding the byproducts of combustion.
  6. Explain the environmental impacts of incomplete combustion, such as the production of harmful pollutants like carbon monoxide, nitrogen oxides, and particulate matter.

Career Film: Arzu Javadova is an Exploration Manager for BP.

Expert Film: Dr Sam Rowe as he demonstrates the 'whoosh bottle'.

Mission Assignment

Comparing Combustion of Fuels

  1. Measure the mass of the fuel (if using a liquid fuel, measure the mass including the burner).
  2. Measure out 10ml of water into the boiling tube. Measure the temperature of the water.
  3. Light the fuel. Then, hold or clamp the boiling tube 2-4 cm over the fuel. At the same time start your stopwatch.
  4. After 1 minute remove the boiling tube from the heat and extinguish the flame.
  5. Measure the temperature of the water and calculate the temperature change.
  6. Measure the mass of the fuel and calculate the change in mass.
  7. Repeat steps 2-5 for a different fuel.
  8. Divide the change in temperature by the change in mass to determine which fuel released more energy.

Mission to Write! Combustion Report

Ask the students to imagine they are a scientific journalist. There has been a house fire and the journalist has been asked to write a newspaper report on the incident, but from a scientific angle. The students should try and explain how the house fire started, how it spread and how it was extinguished. Encourage them to use the key words offered on the handout and to check for accurate spelling, punctuation and grammar.

Differentiated tasks (Support/Challenge)

Support: 

  • Provide scaffolding and simplify the concepts using concrete examples and analogies to help the studentd understand the topic.
  • Use a variety of teaching strategies such as modelling, demonstration and visual aids.
  • Offer additional support and one-to-one guidance to ensure they are keeping up with the class.
  • Provide extra time to complete tasks and worksheets if needed.

Stretch: 

  • Provide clear and concise explanations of the concepts using visual aids and diagrams to aid understanding.
  • Offer a range of examples to support the students’ learning and understanding of the topic.
  • Encourage group work and peer support for discussion and problem-solving.

Challenge: 

  • Offer more challenging questions during class discussion and on the worksheet to stretch the students’ understanding.
  • Allow them to research in more depth and present their findings to the class as an extension activity.
  • Provide additional resources such as scientific articles or videos for independent research and self-directed learning.

Impact & Assessment Opportunities

Plenary

Bring the class back together and ask the groups to share their answers. Use an interactive whiteboard or projector to display a PowerPoint presentation that summarises the key points of the lesson. Finally, ask the students to discuss the environmental implications of incomplete combustion and how it can be prevented.

Teacher Mastery

Combustion (also referred to as burning) is the chemical reaction between a fuel and oxygen to release energy. It is an example of an exothermic reaction because it is a process that transfers energy to the surroundings. Examples of solid fuels are coal and wood, examples of liquid fuels are diesel and gasoline, and examples of gaseous fuels are methane (CH₄, the main constituent of natural gas) and propane (C₃H₈).

Combustion reactions can be classed as complete or incomplete depending on the availability of oxygen. Complete combustion takes places when there is a sufficient supply of oxygen. Complete combustion of a hydrocarbon (i.e. a substance made entirely from the elements carbon and hydrogen) yields carbon dioxide and water as the major products. Incomplete combustion takes place when there is a limited supply of oxygen. Incomplete combustion of a hydrocarbon yields carbon (soot) and carbon monoxide (a poisonous gas) in addition to carbon dioxide and water. Complete combustion typically releases more energy than incomplete combustion.