Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Combustion Question

  1. May 8, 2010 #1
    1. The problem statement, all variables and given/known data

    I have worked out the Stoichiometric equation for this Combustion question, however the second part the Air Intake is only 90% which I have also worked out. My question is, during the element balancing how do I obtain values for b and c.

    2. Relevant equations

    So this is how it currently stands:

    [6.83C + 18H] + 10.20 O2 + 38.34 N2

    b CO2 + c CO + d H2O + 38.34 N2

    3. The attempt at a solution

    I understand this:

    C: 6.83 = b + c
    H: 18 = 2d
    O: 10.20 = 2b + c + d

    I have the answer which is;

    4.57 CO2 and 2.26 CO

    I understand how to obtain the H20 value, but I assumed b + c = 6.83 would just be

    b = 3.41
    c = 3.41

    But this is wrong so could anyone explain how I get the actual values for b and c?

    The final answer looks like this:

    [Fuel] + 10.20 O2 + 38.35 N2

    4.57 CO2 + 2.26 CO + 9 H2O

    Help would be much appreciated.

    Thanks
     
  2. jcsd
  3. May 8, 2010 #2

    jack action

    User Avatar
    Science Advisor
    Gold Member

    2 equation, 2 unknowns:

    equation #1: c = 6.83 - b

    equation #2: c = 10.20 - 2b - d

    d is known from 18 = 2d. Equate both equations to find b, then find c.
     
  4. May 9, 2010 #3
    Hi, thanks for the reply.

    I'm still lost, any chance you (anyone) could walk me through / give the solution to how the end result is obtained?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook