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Homework Help: Is this correct use of the formula? (Pressure, Volume and Temperature)

  1. Oct 31, 2008 #1
    1. The problem statement, all variables and given/known data

    A quantity of gas occupies a volume of 0.5m. The pressure of the gas is 300kPa, when its temperature is 30°C. Calculate the pressure of the gas if it is compressed to half of its volume and heated to a temperature of 140°C.

    2. Relevant equations

    (P1 x V1)/T1 = (P2 x V2)/T2

    3. The attempt at a solution

    P1 = 300 kPa
    V1 = 0.5m (im not sure what unit of volume im meant to be using or converting to so im using as it is)
    T1 = 30°C (303 Kelvin)
    V2 = 0.25m
    T2 = 140°C (413 Kelvin)

    I moved stuff around to make V2 after the "=" Is this right?
    = (300x0.5)/303 = (P2 x 0.25m)/413
    = (300x0.5)/303/0.25x413 = 817.82kPa?
    if not any suggestions?
  2. jcsd
  3. Oct 31, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Yes exactly right.

    You need to be careful with calcs like "(300x0.5)/303/0.25" your caclulator might not do them in the order you think.

    It might be safer to do something like:
    P1V1/T1 = P2V2/T2
    so P2 = P1(V1/V2) * (T2/T1)
    this also makes it obvious that units of the answer are correct.
  4. Oct 31, 2008 #3
    =D Thank You So Much
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