# Isothermal expansion hw problem

1. Nov 28, 2006

Suppose 145 moles of a monatomic ideal gas undergo an isothermal expansion from 1.00m^3 to 4.00m^3, as shown in figure. what is the temp at the beginning and end of this process? how much work is done by the gas during the expansion?

http://www.physics.brocku.ca/Courses/1p23/images/FG18_24.JPG [Broken]

since it is isothermal the temperature is constant correct?
so to solve for the temperature would i just use pv=nrt with the respective values for pressure and volume?
and for the work done W=nrtln(vf/vi)

thanks

Last edited by a moderator: May 2, 2017
2. Nov 28, 2006

### KoGs

You have p_i and p_f, and also v_i and v_f. Can you think of a formula that uses p and v ?

Hint: What are the units for pressure?

3. Nov 28, 2006

so i wouldnt use pv=nrt?

4. Nov 28, 2006

### KoGs

Try it out. Plug in the values of p_i and v_i into that formula.
Then plug in the values of p_f and v_f into that formula.
See what you get.

5. Nov 28, 2006

im getting .332 for the temperature.

6. Nov 28, 2006

and for the work i get 1670.42j

7. Nov 28, 2006

### KoGs

Now you tell me. Is temperature constant?

8. Nov 28, 2006