Thermodynamics( Problem Solving)

justine

4th October 2009 - 08:01 AM

6 m^3 tank contains helium at 400K and is evacuated from atmospheric pressure to a pressure of 740 mm Hg vacuum. Determine (A) mass of helium remaining in the tank, (

mass of helium pump out, © the temperature of the helium falls to 10 degrees Centigrade. What is the pressure in kPa?

Answer: A 0.01925 kg
B 0.7123 kg
C 1.886 kPa

mass 1 = P1V1/R1T1
P(abs) = P(atm) - P(vac) = 20 mm Hg = 2666 pascal
R= 2077.67 pa. m^3/kg. K
mass of helium remaining in the tank

original mass of helium:

m= PV/RT = 101325.024*6/2077.67*400 = .7315 kg

A. m1= P(abs) * V / R * T = 2666 * 6 / 2077.67* 400 = .01925 kg

Mass of helium pump out:

B. m2 = mass original - m1 = .71237 kg

my question is how to get Answer C which is pressure...

rpenner

4th October 2009 - 04:12 PM

10 degrees Celsius = 283.15 kelvin

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