[Jasso66]

Hi. I have a little problem again.
In one of my homework there is asked how air is needed when burning 250kg propane gas (C₃H₆  ) completely in NTP-conditions.

The reaction is (in my opinion) 2C₃H₆ + 9O₂ --> 6CO₂ + 6H₂O 

First you calculate the n(propane gas) and when you compare it with coefficien of n(oxygen) you get the n(oxygen) and use the n(O₂)= V/V_m.(IMO again) I get still wrong answer. Correct answer is V(air)= 2,86x10⁶l.

It would good if someone tells how to calculate this problem. I think that in this problem air=oxygen(O₂).But it looks like it is not so.

Thank you very much beforehand               

[sjb]

Perhaps you need to take account of the fact that air doesn't just consist of oxygen - have a look at http://en.wikipedia.org/w/index.php?title=Earth%27s_atmosphere&oldid=286703854 for instance?

[leve]

Propane is C3H8

[Jasso66]

Yep, I know that but it is quite hard to add up them into the reaction formula. Sorry,  the gas is propene.    

[ARGOS++]

Dear Jasso66;

For STP I get 2.897 10⁶ L Air (21% Oxygen).  I don’t know NTP.

For calculation I applied the recipe/scheme from the Topic "Stoichiometry Problem":   "Stoichiometry Problem (#23'025)"
Therein is also an Example Diagram: How to do a "Stoichiometry Problem".

Therein I used the molar Volume for Oxygen (= 22.71L/mol) for STP.

Good Luck!
                    ARGOS⁺⁺

[Jasso66]

Thanks ARGOS++. NTP= Normal Temperature and Pressure

[Borek]

NTP= Normal Temperature and Pressure

No such thing as 'Normal'. Even STP is ambiguous.

http://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure

[kuwkuw]

first my friend the propane is C3H8 not C3H6 so you have to do the reaction
C3H8+5O2=>3CO2+4H2O
when you compare mols of propane (1) with mols of oxygen (5)

you must calculat number of mols of oxygen that react actullay

number of mols of propane = mass of propane/molecular wight of propane
n=0.25/44 = ??
now you can calculat the number of oxygen that actullay react

NTP = mean Pressure = 1 atm , Tempreature= 273  R = 0.082

from this equation you can react the volume of oxygen

V = n×R×T/P


I think this is the solution