Chemical Forums
Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: neuroid on September 25, 2012, 08:51:06 AM
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After you close the hatch on the international space station, the airlock region is a
nearly perfect vacuum, so you need to start refilling that region with air. Suppose that
you do so by opening up a 10.0 liter tank of 5.00 atm air, allowing the air to expand so
that it now takes up a total volume (tank+ airlock) of 2000 liters. Take the air to be an
ideal gas and assume that the process is isothermal (carried out at constant temperature).
What are q and w for this process? What would q_rev and w_rev have been for the same net
change? Give all of your answers in kJ.
This question has been giving me some problems because it only gives me P_initial and ΔV. I can't calculate w using w = -PΔV because pressure isn't constant (unless w = -ΔPΔV is a viable equation). I can't calculate w_rev, either, through -nRT ln (V_f/V_i) because I don't know the number of moles or the temperature.
Also, how would you calculate isothermal q if it isn't during a phase change? Is this process adiabatic?
Thank you to anyone who offers help.
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Intuitively, do you have any expectation for what the work will be? As the guy expands, what is it doing work against?
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Could you elaborate on that answer? I tried to help, but I'm not certain of the Qrev or Wrev for this process, I understand that for Q and W, it's expanding against the vacuum, but the reversible process confuses me too.
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It's PV BROOOOOOO!
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Use the following equations
P1V1 = P2V2
P1/P2 = T1/T2
P1 = 5 atm, P2 = 1 atm
V1 = 10 litre, V2 = 2000 litre