1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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!

Finding Molar Mass of Unknown Gas

  1. Feb 2, 2010 #1
    Given the following data for a gas, use the equation for the ideal gas law to calculate the molar mass.

    Mass = 0.810 g
    Pressure = 0.954 atm
    Volume = 0.461 L
    Temp = 291 K

    M = mRT/PV = 44.0?
  2. jcsd
  3. Feb 2, 2010 #2
    I won't give you the answer but the following is how you solve the equation


    P=pressure (0.954 atm [use kpa since that is what is required in the ideal gas law thus pressure is 0.954*101.325 kpa = 96.66405 kpa])

    V=volume (0.461 L)

    R=Universal gas constant or 8.314

    T=temperature (291 K)

    m=mass (0.810 g)

    n=mol (unknown)

    M=molar mass (unknown)

    PV=nRT which becomes


    After you get mols, use this formula n=m/M or M=n*m
  4. Feb 2, 2010 #3
    OK I understand now -- thank you!
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook