Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Ideal gas law and pressure

  1. Jun 3, 2005 #1
    hello all. I'm trying to figure out this problem and it's bugging me because it's soooo simple yet i keep getting the wrong answer. here's the problem:

    If 1.00 mol of carbon dioxide gas at 350 K is confined to a volume of 400 cubic centimeters, find the pressure of the gas using the ideal-gas equation.

    Okay.. I know that the ideal gas equation will look like this if I am solving for pressure:

    p = (nRT)/V

    since I want pressure in pascals, then I will convert volume V to cubic meters, and for R constant I will use R = 8.3145 J/mol K

    so far this is the information I have:

    R = 8.3145 J/mol K
    T = 350 K
    n = 1.00 mol
    V = 4 cubic meters

    When I try and solve for pressure, I get 727.5 pascals. I did this 5 times, and I keet getting the same answer. however the book is telling me I'm wrong. Am I not understanding this correct? could this be one of those times the book is wrong? I hope someone can help!
  2. jcsd
  3. Jun 3, 2005 #2
    Your conversion into cubic metres is incorrect, remember it is cubic:



    Use that value for volume and you should calculate the correct answer, which is 7275187Pa or 7.3MPa.
    Last edited: Jun 3, 2005
  4. Jun 3, 2005 #3
    V = 400 cm^3 = 400 * (10^-2 m)^3 = 400 * 10^-6 m^3 = 0.0004 m^3
    I think this is correct value of the volume and if you put it into ideal gas equation you'll get the right answer (i think).
  5. Jun 3, 2005 #4
    thanks to the both of you for your help. i was able to figure it out.. silly mistake. =) night!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook