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# Combustion: When is carbon formed? watch

1. Hello,

I'm just a bit confused as to when carbon is formed? I thought in incomplete combustion it was just (for example):
C4H8 + 4O2 -> 4CO + 4H2O

It says in a question a 'solid and water only' are produced; so is carbon monoxide a solid or a gas and if both, when is it a solid?

Furthermore there is a question that asks 'State a condition which may cause carbon to be formed as a product in the combustion of butane'.

Some clarification would be very helpful!

Thanks.
2. (Original post by itsConnor_)
Hello,

I'm just a bit confused as to when carbon is formed? I thought in incomplete combustion it was just (for example):
C4H8 + 4O2 -> 4CO + 4H2O

It says in a question a 'solid and water only' are produced; so is carbon monoxide a solid or a gas and if both, when is it a solid?

Furthermore there is a question that asks 'State a condition which may cause carbon to be formed as a product in the combustion of butane'.

Some clarification would be very helpful!

Thanks.
Incomplete can produce carbon too

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3. (Original post by Mutleybm1996)
Incomplete can produce carbon too

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But when? Under what condition?
4. (Original post by itsConnor_)
But when? Under what condition?
From what I understand

hydrocarbon + oxygen → carbon monoxide + carbon + water

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5. (Original post by itsConnor_)
But when? Under what condition?
Soot, if there's soot that's carbon.
6. Also, 2CO -> CO2 + C

Who can resist a bit of disproportionation?
7. (Original post by Andy98)
Soot, if there's soot that's carbon.
So for the condition question I would simply put 'soot' ? And how would I write the equation for incomplete combustion when carbon is formed?

Thanks.
8. (Original post by itsConnor_)
So for the condition question I would simply put 'soot' ? And how would I write the equation for incomplete combustion when carbon is formed?

Thanks.
No you wouldn't simply put soot. What level is it?
9. So, what you are looking for is the formulas and word equations of combustion:

Complete Combustion occurs when a fuel burns in plenty of oxygen.
Word Equation is methane + oxygen --> carbon dioxide + oxygen

Incomplete combustion's word equation =
fuel + oxygen --> carbon monoxide + water
fuel + oxygen --> carbon + water
Toxic gas (carbon monoxide) and soot (carbon) is made during incomplete combustion.

Balanced symbol equations:

Complete combustion:
CH4 + 2O2 --> CO2 + 2H2O

Incomplete combustion:
2CH4 + 3O2 --> 2CO + 4H20 when carbon monoxide is released
OR
CH4 + O2 --> C + 2H2O when carbon is released

As you can see complete combustion occurs when a fuel burns in plenty of oxygen, which is why it releases more energy than incomplete combustion.

Therefore, incomplete combustion doesn't release oxygen only but instead water.
This means that incomplete combustion occurs due to a lack of oxygen in the air and that would release more carbon monoxide than carbon dioxide.

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Updated: February 1, 2015
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