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!

Chemistry problem involving gas laws

  1. Oct 8, 2008 #1
    A 2.80g sample of an unknown chlorofluorocarbon is decomposed and produces 552mL of chlorine gas at a pressure of 756 mmHg and a temperature of 298K.
    What is the percent chlorine (by mass) in the unknown chlorofluorocarbon?


    PV= nRT
    D= m/v


    Ok, so for this problem I tried using the PV=nRT (756*.552=n*62.364*298) equation to solve for n and I got 0.02245 mol. And from that, I figured the molar mass was 124.69 g/mol (having used the mass of 2.80 to derive this answer). And then I tried to set up an algebraic equation with variables to solve for the mass percent. I used the equation (1-x)(31.008) + 35.45x = 124.69. The (1-x) represents the Carbon and Fluorine components of the compound, and the 31.008 is their combined molar mass. The 35.45 is the molar mass of Clorine, and by solving this equation i got 21.09, but this was incorrect. So what should i do?
     
    Last edited: Oct 8, 2008
  2. jcsd
  3. Oct 8, 2008 #2

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    How many grams of chlorine are in 0.02245 mol of Cl2?

    Compare that to 2.80 g.
     
  4. Oct 8, 2008 #3
    but we don't know how many grams we have of chlorine...?
     
  5. Oct 8, 2008 #4

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    You know how many moles and how many grams/mole for chlorine. Use that.
     
  6. Oct 8, 2008 #5
    okay thank you i got it!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Chemistry problem involving gas laws
  1. Chemistry Gas Laws (Replies: 1)

Loading...