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Homework Help: Density of Gas

  1. Nov 5, 2006 #1
    Heres a problem on a take home quiz im doing, but i cant figure out how to get past the first step?!

    The density of helium gas at 0°C is 0.179 kg/m^3. The temperature is then raised to 100°C, but the pressure is kept constant. Assuming that Helium is an ideal gas, calculate the new density of the gas.

    Heres the equations i have:
    P1V1 / T1 = P2V2 / T2

    In order to work this equation i need volume, but i have a density, heres the equation i think i need:

    roe = m / V
    (density = mass / volume)

    How do i work this if i dont have mass or volume?!
  2. jcsd
  3. Nov 5, 2006 #2

    Andrew Mason

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    Science Advisor
    Homework Helper

    You have to find the proportional increase in volume: V2/V1. You know P1 and P2 (they are the same. You know T1 and T2. All you have to find is V2/V1.

  4. Nov 5, 2006 #3
    You know the mass of the gas doesn't change. Try putting the density formula into the equation, you will find that they cancel out.
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