Isothermally Expanding Question

  • #1
PsychonautQQ
784
11

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;-(
 

Answers and Replies

  • #2
DrClaude
Mentor
7,878
4,489
3Pi = Pf
does this lead to Vi = 3Vf? since PV/T = c and T doesn't change?
Yes.

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.
 
  • #3
22,145
5,079
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
 

Suggested for: Isothermally Expanding Question

Replies
8
Views
302
Replies
3
Views
365
Replies
3
Views
213
  • Last Post
Replies
13
Views
430
Replies
7
Views
381
Replies
2
Views
592
  • Last Post
Replies
4
Views
230
  • Last Post
Replies
2
Views
182
  • Last Post
Replies
8
Views
247
Top