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COMBUSTION

Combustion is the chemical term for burning

There are 3 factors required for combustion, remove one of these and combustion won't happen properly. This triangle is known as the fire triangle


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TYPES OF COMBUSTION

Combustion is the combination of a fuel (like an alkane or alcohol) with oxygen and heat

If we change the amount of oxygen available we can get different types of combustion


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BUNSEN BURNER FLAMES
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The Bunsen Burners we use at school use a mixture of alkane gases like propane and butane


When the airhole is closed we are limiting the amount of oxygen to combine with the gas, this produces a yellow flame; this is incomplete combustion

When the airhole is open we are providing maximum oxygen to the gas, this produces a blue flame; this is complete combustion

The blue flame is much hotter and we say that it is more energy efficient as it provides more heat for the same amount of gas used



REACTIONS AND EQUATIONS

COMPLETE COMBUSTION - always produces water and carbon dioxide (and lots of heat energy)


This is the word and balanced chemical equation for the complete combustion of methane
This is the word and balanced chemical equation for the complete combustion of methane

Here is another one - this time with propane


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INCOMPLETE COMBUSTION

Incomplete combustion can produce 2 different products depending on the amount of oxygen present

1) Carbon monoxide (CO) and water

2) Soot (C) and water


ALCOHOLS

Alcohols usually only undergo complete combustion, this is because they have an oxygen in their formula


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WRITING WORD AND BALANCED CHEMICAL EQUATIONS

For achieved you need to be able to write a word equation

e.g. methane + oxygen --> carbon dioxide + water

For merit and excellence you need to be able to write a balanced chemical equation like those in the diagrams above

PRACTICE QUESTIONS

Write a word equation and balanced chemical equation for the following

1) Complete combustion of ethane

2) Incomplete combustion of heptane producing carbon monoxide

3) Complete combustion of ethanol

4) Incomplete combustion of hexane producing carbon (soot)



http://www.chemistryhelp.net/basic-chemistry/complete-and-incomplete-combustion