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Diesel Fuel Combustion

08/11/2013 4:32 AM

C7H13 + 10O2 + 39N2 = x1 CO2 + x2 H2O + x3 N2 + x4 O2 + x5 CO + x6 NOx + x7 CxHy please help me to balance this equation

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#1

Re: diesel fuel combustion

08/11/2013 4:53 AM

I don't think there's enough information for a unique solution. And you forgot the argon (as well as the CO2 on the left side, and also how to use subscripts.)

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#3
In reply to #1

Re: diesel fuel combustion

08/11/2013 7:32 AM

For instance, the solution I like best is:
x1 = x2 = x4 = x5 = x6 = 0
x3 = 39; x4 = 10; x7 = 1
CxHy = C7H13.

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#5
In reply to #3

Re: diesel fuel combustion

08/11/2013 7:59 AM

I prefer CH3CH2OH, usually with a splash of soda water.

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#2

Re: diesel fuel combustion

08/11/2013 6:17 AM

There are 3 hydrocarbons (isomers) with the formula C7H13 - none of which could be regarded as being present in diesel fuel, although there may always be the minutest of quantities present. I don't know where you got this formula from. Diesel is normally regarded as a mixture of hydrocarbons from C8 to C21 - possibly you have been given C14H26 as the "average composition" which has been turned into the empirical formula of C7H13, although I see no point in doing that.

As for balancing the equation - that's your homework. You will only learn by doing it yourself!

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#4
In reply to #2

Re: diesel fuel combustion

08/11/2013 7:56 AM

C8H18 + 12.5O2 + 47N2 = x1 CO2 + x2 H2O + x3 N2

+ x4 O2 + x5 CO + x6 NOx + x7 CxHy

another dissociation formula is

2CO + O2 = 2CO2

NOW what do u say

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#6
In reply to #4

Re: diesel fuel combustion

08/11/2013 10:29 AM

It is trivially easy to generalize from a previous example.

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#10
In reply to #4

Re: diesel fuel combustion

08/12/2013 3:14 AM

The stoichiometry class is just down the corridor, third door on the right. Yes, that's it. Have a splendid day.

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#7

Re: Diesel Fuel Combustion

08/11/2013 12:48 PM

I believe that's gasoline....

C7H13 +10:25O2 +38:54N2 ! 7CO2 +6:5H2O+38:54N2

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#8

Re: Diesel Fuel Combustion

08/11/2013 10:46 PM

The answer is soooo simple!!! All that gibberish = 3. What was so hard about that???????????

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#9

Re: Diesel Fuel Combustion

08/12/2013 12:20 AM

equation is wrong check the number of nitrogen mollecules and repost, cheers

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#11

Re: Diesel Fuel Combustion

08/12/2013 5:40 AM

Nitrogen oxides are a very minor part of what is going on, so they can be ignored with very little effect. Once that is done, assume complete combustion and make the numbers of atoms each side balance-up. It's only simple arithmetic.

How has C7H13 arrived? Hydrocarbons do not usually form with odd numbers of hydrogen atoms. C7H8 would be toluene, for example. C7H14 is a heptene, and C7H16 is a heptane.

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#12

Re: Diesel Fuel Combustion

08/12/2013 9:06 PM

C14H26 is not equal to 2(c7h26)

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#13

Re: Diesel Fuel Combustion

08/12/2013 9:29 PM

Complete or stoichiometric combustion for a diesel engine is where I would start the equation.

The theoretical air to diesel fuel mix is, 14.5 kg of air to 1kg of fuel, however this can vary with diesel engines that can provide excess air to 150% or more to ensure complete combustion. The diesel fuel type or quality can also change this ratio.

eg for perfect stoichiometric mix, C3 H8 +o2 = Co2 + H2o

The N2 is not taken in to count as it doesn't change in the heating inside the engine.

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#14

Re: Diesel Fuel Combustion

08/12/2013 10:16 PM

If this is homework, read #14 in the FAQs.

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