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1. Oct 27, 2015

krootox217

1. The problem statement, all variables and given/known data
I have the following task:

2. Relevant equations

3. The attempt at a solution

I already managed to do a), but how do I solve b) ? What is this Joule-Coefficient and how can I calculate this for the two different kinds of gases without any given values?

2. Oct 27, 2015

Staff: Mentor

The equation for the Joule-Coefficient is given in the problem statement. Are you asking what it means physically?

As far as the two different kinds of gases are concerned, you are supposed to do it algebraically. For an ideal gas, I assume you know PV=nRT. Do you know the P-V-T equation for the van der Waals approximation to real gas behavior?

Chet

3. Oct 28, 2015

krootox217

Hi,

Does this mean, that I have to do it like this:

And now just simplify?

4. Oct 28, 2015

Staff: Mentor

Yes.

5. Oct 28, 2015

krootox217

Thanks a lot!

Is this already the result, or can I simplify it even more?

6. Oct 28, 2015

Staff: Mentor

If pV=nRT, what is pV-nRT equal to?

If $p=\frac{RT}{V_m-b}-\frac{a}{V_m^2}$, what is $p-\frac{RT}{V_m-b}$ equal to?

Chet

7. Oct 28, 2015

krootox217

0

-a/(Vm)^2

And this means the coeficient is in the upper case 0 and in the lower case -a/(Vm)^2 and therefore these are the final results?

8. Oct 28, 2015

Staff: Mentor

Yes, but don't forget to divide by Cv.

9. Oct 28, 2015

krootox217

Oh I nearly forgot, thank you!

This means it is in the first case still 0 and in the second case -a/((Vm)^2*Cv)

10. Oct 28, 2015

krootox217

Btw. I'm new here. Is there a possibility to give a plus point or something like that for your help?

11. Oct 28, 2015

Staff: Mentor

Please excuse my manners. Welcome to Physics Forums!!!

If you want to thank someone for their help, click Like at the bottom of their post.

Chet