Combustion reactions and impact on climate
Combustion is burning a substance in oxygen
Combustion is an example of an irreversible exothermic chemical reaction.
Exothermic means a chemical reaction that releases heat energy.
Complete combustion of hydrocarbons produces carbon dioxide gas and water
Incomplete combustion produces carbon monoxide gas and carbon (particulates, soot)
methane gas + oxygen gas → carbon dioxide + water vapour
petrol + oxygen → carbon dioxide gas + water vapour
paraffin (from candle wax) + oxygen → carbon dioxide gas + water vapour
coal + oxygen → carbon dioxide gas + water vapour
Simulation of products of combustion (click here)
Effects of combustion
1. Carbon dioxide contributes to global warming and climate change
There are two main reasons why the amount of carbon dioxide in the atmosphere is gradually increasing:
1. Humans are burning fossil fuels
2. Humans are cutting down forests
Fuse school video link (click here)
Effects of global warming (click here)
Simulation of global warming (click here)
2. Acid rain (caused by sulfur dioxide and nitrogen oxide gases)
3. Global dimming due to carbon particulates (unburnt carbon, soot)
4. Carbon monoxide is a respiratory poison
Carbon monoxide gas detectors, placed in home and other public places, can save lives
The ‘Greenhouse effect’
Gases in the atmosphere, like carbon dioxide, will allow sunlight energy to shine onto the Earth’s surface, but do not allow the heat energy to escape back into space.
Aerosol and methane gas emissions can also contribute to greenhouse effect.
The ‘Greenhouse’ effects include:
1. Global temperature increases (0.2ºC every 10 years)
2. Melting ice sheets and glaciers and rising sea levels
3. Changes in dry seasons and rainy seasons.
What we can do to reduce our release of greenhouse gases
1. Reduce burning fossil fuels
2. Be more energy efficient
3. Use alternative energies e.g. biofuel or solar power
4. Protect forests
4. Reducing fertilisers (nitrogen oxide) and storage of manure (methane)