fuel oil combustion equation to balance

[Nicolas-G]

Hello,
In a homework assignment (3ème), I have this question:
write the balance equation for the combustion of fuel in the air (C21H44)
Problem:
If I solve it, it will be vague (we have seen that the nitrogen and oxygen levels were respectively 70% and 20%)
the problem is that I do not know how to perform balance equation with percentages
merci beaucoup

[Remundo]

Ah ... New concept ... Econologiacadomia !!

Well, I'm still not going to do all the work for you ...

But combustion is the reaction with OXYGENE that is present in O2.

If it is complete, it gives H2O and CO2 only from CxHy

So

C21H44 + ???? O2 -------> ??? CO2 + ??? H2O

Methodology:
1. Balance the carbons (right)
2. Balance the hydrogen (right)
3. Set the number of O2 (left) to balance the oxygen


You would not be a little lazy?

[Nicolas-G]

thank you very much but what bothered me was that there was the word air and not dioxygen
for me the air is oxygen +

[Nicolas-G]

Find:
C21H44+ 11O2--->21CO²+22H2O

Edit: oupppps
C21H44+ 53O2--->21CO²+22H2O

[Christophe]

Everything is here: https://www.econologie.com/equation-de-c ... s-638.html

ps: CO² I doubt that teachers like ... CO2 is better ... or so you have to note H²O too ...

[Remundo]

Nan nan ... not 53 O2, look right ... 21O2 and 22O, how much in O2 ??

[Christophe]

CnH(2n+2) + (3n+1)/2*(O2+3.76N2) --> nCO2 + (n+1)H2O+(3n+1)/2*3.76N2

Duty Internet finished

[Remundo]

RRRRRRRRoooooooohhhhh!

Christophe, you ruin all my efforts of "active pedagogy"

For the specific question with mass%, it seems complicated for a level 3ème, but who knows? ...

@+

Everything is here: https://www.econologie.com/equation-de-c ... s-638.html

ps: CO² I doubt that teachers like ... CO2 is better ... or so you have to note H²O too ...

[Remundo]

And we notice that N2 does not react ... In reality, the heat can lead to Nox, the famous nitrogen pollutants engines ... If you say all that to your teacher, you have 20 / 20!

Go, bye bye!

CnH(2n+2) + (3n+1)/2*(O2+3.76N2) --> nCO2 + (n+1)H2O+(3n+1)/2*3.76N2

Duty Internet finished

[Christophe]

For the specific question with mass%, it seems complicated for a level 3ème, but who knows? ...

The mass and volume composition of the air are very close because N2 and O2 are very close atomically (see https://www.econologie.com/forums/tableau-pe ... t4727.html ) and are all 2 bi-atomic gases so whose mole takes the same volume.

It is played 2 or 3% ... I think it is 23% mass of O2 ...