Combustion of petroleum (1 Viewer)

[lilchezza]

Does anyone have any, like ANY info on the combustion of petroleum? All i know is that it is the burning in air, and that's obvious. :burn:

 

[Riviet]

Combustion of octane: C₈H_18(aq) + 17/2.O_2(g) -> 8CO_2(g) + 9H₂O_(l)

 

[TAZ33]

Octane is the average molecule found in petroleum, although there are other ones in the range of 5 carbons to 12 carbons. Their reactions are similar to the one posted by Riviet

 

[kazan]

the reaction for any alkanol in plentyful air


alkanol + oxygen --> water + carbon dioxide

insufficient air

alkanol + insufficient oxygen --> water + carbon monoxide

little air at all

alkanol + minimal air --> water + soot ( pure carbon)


the last two reactions sometimes combine.

just put your alkanol in the equation ( petrol is octane normally but as posted above, it varies) then look in the question for its discription of the oxygen supply. decide which formula to use, then balance the equation.

its exothermic(duh)

depending on the alkanol the heat of combustion varies. i cant rember octance of the top of my head.


is that what you wanted? or was it something else?

 

[wasssup]

can u guys help me out on this question:

incomplete combustion of 1-propanol
is it propanol + oxygen --> carbondioxide + carbonmonoxide + carbon + water?

 

[pLuvia]

propanol + oxygen --> carbon monoxide + carbon + water
OR
propanol + oxygen --> carbon + water

 

[kloudsurfer]

propanol + oxygen --> carbon monoxide + carbon + water
OR
propanol + oxygen --> carbon + water

Can't the products also be carbon + carbon dioxide + water?
or carbon dioxide + carbon monoxide + water?

 

[Riviet]

Can't the products also be carbon + carbon dioxide + water?
or carbon dioxide + carbon monoxide + water?

Probably, as these different reactions are occuring when fuels undergo combustion. You should stick to the ones pLuvia mentioned as these are easier to balance.

 

[wasssup]

excuse me but my teacher said that something about incomplete combustion of long chain alcohols like hexanol will have a carbon dioxide + carbon monoxide + carbon + water ?

because the way my teacher explained it kinda made sence in that the -OH group will be combusted completely thus forming the CO2 and H2O and the rest of the chain will be incomplete thus giving us the CO + C

is this true?
thank you

 

[Riviet]

To be honest, I don't know as I wasn't taught that when I did the module. But you're right in saying that C and CO can also be formed in the reaction.

 

[kloudsurfer]

Probably, as these different reactions are occuring when fuels undergo combustion. You should stick to the ones pLuvia mentioned as these are easier to balance.

Ahh ok. Thanks. I was just taught that and I was worried that iyt was wrong.

I have a few random questions.

When you find the heat of combustion using the formula triangle H = -m C triangle T, should the answer be a negative or a positive? I asked my teacher but he wasnt much help.

Also, why do some fuels burn completely in air and some dont? Does it have anything to do with the chain length?

 

[rama_v]

Ahh ok. Thanks. I was just taught that and I was worried that iyt was wrong.

I have a few random questions.

When you find the heat of combustion using the formula triangle H = -m C triangle T, should the answer be a negative or a positive? I asked my teacher but he wasnt much help.

Also, why do some fuels burn completely in air and some dont? Does it have anything to do with the chain length?

Enthalpy is measured in kJ/mol and is negative for exothermic reactions. It is basically a measurement of the change in internal energy of a system, delta E, when volume change is negligable in a reaction. You need to be aware that negative delta H does not mean that the reaction is spontaneous.

What you need to know is that the more negative the delta H, the more the heat released by the reaction.

Fuels will undergo complete combustion under the right conditions. This means that the fuel will combust completely when there is enough moles of oxygen available to combust with the moles of whatever fuel you have. Smaller carbon chains need less moles of oxygen to combust, so they will combust completely far easier than long chain hydrocarbons.

 

[kloudsurfer]

Enthalpy is measured in kJ/mol and is negative for exothermic reactions. It is basically a measurement of the change in internal energy of a system, delta E, when volume change is negligable in a reaction. You need to be aware that negative delta H does not mean that the reaction is spontaneous.

What you need to know is that the more negative the delta H, the more the heat released by the reaction.

Fuels will undergo complete combustion under the right conditions. This means that the fuel will combust completely when there is enough moles of oxygen available to combust with the moles of whatever fuel you have. Smaller carbon chains need less moles of oxygen to combust, so they will combust completely far easier than long chain hydrocarbons.

Ahhh...thats what i thought. Its just that my teacher keeps writing it as a positive and its been confusing me.

So...smaller chained hydrocarbons need less moles of oxygen to combust because one mole of a smaller hydrocarbon is smaller (duh!) than one mole of a larger hydrocarbon?

Thanks

 

[rama_v]

Yep, thats basically it.

 

[onebytwo]

Combustion of octane: C₈H_18(aq) + 17/2.O_2(g) -> 4CO_2(g) + 9H₂O_(l)

that 4 should be an 8
a quick correction

 

[Riviet]

^ Fixed, thanks for spotting that onebytwo.