COMBUSTION AND FUEL
Performance Task
You and your group will be given a source of energy and have to
convince the Department of Energy of the Philippines that your
source is the best to power the Philippines into the future.
But first we must understand how fuels burn, and their
effects on the planet.
Fuels react with oxygen to release energy.
Complete combustion happens in a plentiful supply of air.
Incomplete combustion occurs when the supply of air is
limited.
Complete combustion releases more energy than incomplete
combustion.
Incomplete combustion also creates carbon monoxide, and more
soot. Which we saw in the lab.
Combustion
Fuels are substances that react with oxygen to release useful
energy. Most of the energy is released as heat, but light energy is
also released.
About 21 per cent of the air is oxygen. When a fuel burns in
plenty of air, it receives enough oxygen for complete
combustion.
Methanol- CH40
Ethanol- C2H60
Propanol- C3H80
Butanol- C4H10O
Fuels such as natural gas and petrol contain hydrocarbons.
The fuels such as isopropanol, ethanol and the other fuels
from the lab also contain these hydrocarbons.
Complete Combustion
Complete combustion needs a plentiful supply of air so
that the elements in the fuel react fully with oxygen.
When these fuels burn completely it’s known as complete
combustion
In general for complete combustion:
hydrocarbon + oxygen → carbon dioxide + water
Incomplete Combustion
Incomplete combustion occurs when the supply of air or oxygen is poor.
Water is still produced, but carbon monoxide and carbon are produced
instead of carbon dioxide.
In general for incomplete combustion:
hydrocarbon + oxygen → carbon monoxide + carbon + water
The carbon is released as soot. Carbon monoxide is a poisonous gas,
which is one reason why complete combustion is preferred to
incomplete combustion.
Gas fires and boilers must be serviced regularly to ensure they do not
produce carbon monoxide.
Bunsen Burner
The Bunsen Burner uses methane CH4 as its fuel which is a
hydrocarbon
The air hole allows for complete or
incomplete combustion to occur.
methane + oxygen
→
carbon dioxide + water
When the air hole is opened fully a blue flame is
produced, and complete combustion occurs.
A very hot, blue flame is produced.
Air hole closed
When the air hole is closed the natural gas can only mix with air at the mouth of
the chimney. Incomplete combustion occurs as a result:
methane + oxygen
→
carbon monoxide + carbon + water
The yellow flame is often called the safety flame
A yellow flame is produced, which transfers less heat energy than the blue flame.
The yellow flame is brighter than the blue flame because the specks of carbon
glow when heated.
GREENHOUSE EFFECT
http://www.youtube.com/watch?v=dP-tg4atr5M
ATMOSPHERE GASES
GREENHOUSE GASES
Excluding water Vapor which can be up to 40%