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Which unit of pressure is used in the ideal gas law?

  1. Sep 9, 2010 #1
    The ideal gas law states that pressure (P) is equal to the product of density (N), the ideal gas constant (R) and temperature (T):

    P = N x R x T

    I can't figure out which unit the pressure is actually in, although it does seems to work out as the figure I'm supposed to get with a 11706.85° increase in temperature is around 40x the pressure at 293.15° Kelvin:

    N = 1.204 kg/cubic metre
    R = 8.314472
    T = 293.15
    P = 2934.61

    N = 1.204 kg/cubic metre
    R = 8.314472
    T = 12000
    P = 120127.49

    Thank you for considering this!

    - Gordon
  2. jcsd
  3. Sep 9, 2010 #2


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    Science Advisor

    The units must only be dimensionally correct. Absolute values are used for pressure and temperature.

  4. Sep 9, 2010 #3
    You need to start by writing the ideal gas law as P =RT/V, and substituting in the units for

    R (joules/mol °K), T (°K), and V (m3).

    [added] In this situation, V is actually in units of m3/mol

    Bob S
    Last edited: Sep 9, 2010
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