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!

KJ per hydrocarbon "empirical formula unit"

  1. Oct 15, 2014 #1
    1. The problem statement, all variables and given/known data
    A sample of a hydrocarbon is combusted completely in O2(g) to produce 19.65gCO2(g), 4.023gH2O(g), and 280kJ of heat.

    Calculate the value of ΔH∘f per empirical-formula unit of the hydrocarbon.

    2. Relevant equations
    None I know of

    3. The attempt at a solution
    Previous calculations found that the hydrocarbon had a mass of 5.811g.

    Per empirical formula unit: (I determined the empirical formula to be CH, which was correct)

    molar mass of CH = 13.018g/mol

    5.811g / 13.018g/mol = 0.447 mol CH

    280kJ/0.447 mol = 627.266 kJ/mol

    My final answer was 627.266 kJ/mol but that was not correct.

    Am I interpreting the meaning of "empirical-formula unit" correctly?

    Any help is greatly appreciated.
     
  2. jcsd
  3. Oct 16, 2014 #2

    Borek

    User Avatar

    Staff: Mentor

    Looks OK to me, perhaps it is just a matter of significant figures, or some rounding error?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: KJ per hydrocarbon "empirical formula unit"
  1. Naming of hydrocarbons (Replies: 7)

  2. Hydrocarbons analysis (Replies: 18)

  3. Naming a hydrocarbon (Replies: 4)

Loading...