00:01
Derive the thermodynamic identity for f and that relates a variation to variations in t, v, and n.
00:10
So we have our helmholtz free energy, and if we differentiate this, we can write df equal to du minus sdt minus tds.
00:25
And so df is equal to negative sdt minus pdv plus mu dn.
00:33
So we want to derive an identity from this problem.
00:38
So we find that p is going to be equal to negative del f del v, keeping temperature and n constant.
00:46
S is negative partial derivative of this f with respect to t, keeping volume and n constant.
00:54
And then mu is del f del n, keeping s and temperature constant.
01:01
Now for v, we would like to derive a maxwell relation.
01:07
We want to differentiate our equation, our first equation, with respect to t.
01:14
We can differentiate del p del t with respect to v.
01:21
And so we get del squared f del t del v.
01:26
Differentiating del s del v with respect to t, we get del squared f of del v del t.
01:35
And so by these two equations, we get another equation, that they're equal to the same thing.
01:41
Now we can differentiate our equation two with respect to n...