Isothermally Expanding Question

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SUMMARY

The discussion focuses on calculating the work done during the isothermal expansion of an ideal gas, specifically two moles at a constant temperature of 338K. The key equation used is the ideal gas law, PV = nRT, which allows for the substitution of pressure in terms of volume. The correct approach involves integrating the work done, W = ∫PdV, where P is expressed as nRT/V. The relationship between initial and final volumes is established, confirming that the initial pressure is three times the final pressure.

PREREQUISITES
  • Understanding of the Ideal Gas Law (PV = nRT)
  • Knowledge of isothermal processes in thermodynamics
  • Familiarity with calculus, specifically integration
  • Concept of work done in thermodynamic systems
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  • Learn about the implications of the ideal gas law in different thermodynamic scenarios
  • Explore the concept of pressure-volume relationships in gas laws
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This discussion is beneficial for students studying thermodynamics, particularly those tackling problems related to ideal gases and isothermal processes. It is also useful for educators and professionals in physics and engineering fields.

PsychonautQQ
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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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