1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Hydrocarbon empirical formula question

  1. Oct 14, 2009 #1
    1. The problem statement, all variables and given/known data
    Q. A Hydrocarbon (CnHm) is burned completely in oxygen to produce a mixture of CO2 and H2O. The total pressure of mixture is 1.200 atm and partial pressure of H2O is 0.686 atm. What is empirical formula of Hydrocarbon



    2. Relevant equations

    pV=nRT
    pa/ptotal = na/ntotal

    3. The attempt at a solution
    The answer is C3H8 aka Propane

    Im so confused! I don't even know where to start with this!!
     
  2. jcsd
  3. Oct 14, 2009 #2

    Delphi51

    User Avatar
    Homework Helper

    Find the partial pressure for the CO2. The partial pressures of the gases are proportional to the number of molecules, so you've immediately got the ratio of the number of H2O molecules to the number of CO2 molecules. This is almost m/n, but note that because of the H2 there are twice as many H's as H2O's, so you've really got the ratio of m/2 to n. It should then be easy to get the ratio m to n. Then you start guessing - if n=1 does m work out to an even number? If not, try n = 2 and so on.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Hydrocarbon empirical formula question
  1. Formula question (Replies: 1)

Loading...