Isothermally Expanding Question

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The discussion focuses on calculating the work done when two moles of an ideal gas are compressed isothermally at 338K until the pressure triples. Participants clarify that the ideal gas law (PV=nRT) is essential for solving the problem, particularly in determining the relationship between initial and final volumes. It is emphasized that the work done should be calculated using an integral approach, substituting the ideal gas law into the work equation. The correct interpretation of the pressure and volume relationship is crucial, as the pressure is not constant during the process. Ultimately, understanding the integration of the ideal gas law is key to finding the solution for work done in this scenario.
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Homework Statement


Two moles of an ideal gas are compressed in a cylinder at a constant temperature at 338K until the original pressure is tripled. Calculate the amount of work done.



Homework Equations


PV=nRT
PV/T = c


The Attempt at a Solution


I don't know how to incorporate the cylinder information into this problem.. or get anywhere at all really.
3Pi = Pf
does this lead to Vi = 3Vf? since PV/T = c and T doesn't change?

W = PdV = nRdT..?
..halppp;-(
 
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PsychonautQQ said:
3Pi = Pf
does this lead to Vi = 3Vf? since PV/T = c and T doesn't change?
Yes.

PsychonautQQ said:
W = PdV = nRdT..?
No, that doesn't make sense since P is not constant and T is.

You need the formula for work as an integral over dV and use the ideal gas law to substitute for T which is constant.
 
If the temperature is constant, what is the ratio of the initial volume to the final volume? Your equation for the work is correct (if you use the convention that dW is the work done on the surroundings by the system). Just substitute nRT/V for P and integrate.

Chet
 

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