Maths help

Hello all.

I would like help with this question if its ok.

Assuming that the free energy of a substance, G, is a function of pressure, p abd temperature, T, i.e G=G(p,T)

(a) write an expression for the total differential change in the free energy, dG.

(b) Comparing the results from above with the equation

dG = V dp - SdT

Write down expressions for
(i) (DeltaG/Deltap)T
and
(ii)(deltaG/DeltaT)p

small T and p are meant at X constant


Any help would be appreciated

Hm, can I recommend that you read "Equilibrium Thermodynamics" by Adkins or "Statistical Physics" by Mandl, like you're supposed to when you get stuck on a problem sheet? Or maybe even the lecture notes.
No offense, but you're really better off reading up on this stuff and making sense of it yourself, or handing in a duff set of answers, getting a bad mark and then getting some help, because it is fairly fundamental thermodynamics and you'll need it later.

You'll thank me.

Quote:

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Originally Posted by zaza

Hm, can I recommend that you read "Equilibrium Thermodynamics" by Adkins or "Statistical Physics" by Mandl, like you're supposed to when you get stuck on a problem sheet? Or maybe even the lecture notes.
No offense, but you're really better off reading up on this stuff and making sense of it yourself, or handing in a duff set of answers, getting a bad mark and then getting some help, because it is fairly fundamental thermodynamics and you'll need it later.

You'll thank me.

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zaza,

i think it's pure Mathematics (differentiation and integration) which is used extensively in Physics. he is just asking for a differentiation of a function with 2 variables and then comparing it with a given equation to get the equations (or values) for V and S (or -S).

I know what he's after. But honestly, if you skip out on this stuff and don't get your head round it, then there's a lot of thermodynamics that isn't going to make a lot of sense.
The answers to these very questions are in just about every thermo textbook I've read, so fundamental and typical are they. It's worth looking up.

Thanks for the help guys