1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Change in pressure using PV=nRT

  1. Nov 17, 2008 #1
    1b]1. Gas is confined in a tank at a pressure of
    6.5 atm and a temperature of 9.4◦C.
    If half of the gas is withdrawn and the
    temperature is raised to 62.4◦C, what is the
    new pressure in the tank? Answer in units of

    2. PV=nRT
    Ti= 9.4 C + 273= 282.4K
    Tf= 62.4 C +273= 335.4K

    3. PV= nRT, n and R are constants, therefore I used PV= T
    So, initially, 6.5atmVi= 282.4K giving, Vi = 43.446

    I then used (1/2) 43.446 as Vf and solved for Pf
    Pf= Tf/ Vf=> 15.439 atm

    But this isn't right, I know. What am I missing?? .
  2. jcsd
  3. Nov 17, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    My thought would be that "half of the gas is withdrawn" means that the number of particles n is halved, and the volume is kept constant, not the other way around.
  4. Nov 17, 2008 #3
    It doesn't mention the volume has been reduced by a half, the amount of gas has been reduced by a half so you need to use 0.5n.
  5. Nov 17, 2008 #4
    Thanks to the both of you!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook