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!

Molecular formula of hydrocarbon

  1. Jan 15, 2008 #1
    1. The problem statement, all variables and given/known data

    0.1 dm^3 of a gaseous hydrocarbon may require 0.45 dm^3 of oxygen for a complete combustion to give 300 cm^3 of Carbon dioxide. All volumes are measured in the same environment. Calculate the molecular formula of the hydrocarbon.

    3. The attempt at a solution

    i tried getting the gdc of 10, 30 and 45 =90. and the have like

    9 CxHy + 2 O2 --> 3 CO2 + H2O

    but I cannot go further than this. please help. Thanks.
     
  2. jcsd
  3. Jan 15, 2008 #2
    as for the formula you have taken.. i don't understand why you've taken the GCD, but it is fundamentally wrong as the oxygen is not balanced on both sides [and neither is carbon or hydrogen].

    What you need is a equation which is prefixed and suffixed by variables on both the sides to get you a linear equation which you can then solve...
     
  4. Jan 15, 2008 #3

    chemisttree

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Can you think of a way to calculate the amount of carbon in CO2 and hydrogen in H2O? You have a good start here:
    I've removed the prefixes you had (the '9', '2' and '3'). Can you solve it in terms of 'x' and 'y'?
     
  5. May 26, 2009 #4
    CxHy + (x+y/4)O2 --> xCO2 +y/2H2O

    thats the correct answer from ccea spec for alevel chemistry =]
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Molecular formula of hydrocarbon
  1. Molecular formula (Replies: 2)

  2. Molecular formula (Replies: 1)

Loading...