How to Solve for Joule-Coefficient in a Gas System?

[krootox217]

Homework Statement

I have the following task:

Homework Equations

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?

 

[Chestermiller]

Homework Statement

I have the following task:

Homework Equations

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?

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

 

[krootox217]

Hi,

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

And now just simplify?

 

[Chestermiller]

And now just simplify?

Yes.

 

[krootox217]

Thanks a lot!

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

 

[Chestermiller]

Thanks a lot!

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

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

 

[krootox217]

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

0

If p=RTVm−b−aV2mp=\frac{RT}{V_m-b}-\frac{a}{V_m^2}, what is p−RTVm−bp-\frac{RT}{V_m-b} equal to?

-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?

 

[Chestermiller]

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?

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

 

[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)

 

[krootox217]

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

 

[Chestermiller]

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

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