Which should I use to prove this?

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The discussion revolves around the application of thermodynamic equations, particularly focusing on the relationship between entropy (s), internal energy (u), and enthalpy (h) at constant volume. Participants are trying to derive equations involving partial derivatives while keeping volume constant, specifically discussing the equation Tds = du + pdv. There is a suggestion to utilize Maxwell relations to facilitate the derivation of these equations. One participant expresses confusion about Maxwell relations and seeks guidance on how to proceed with the calculations. The conversation emphasizes the need for a deeper understanding of thermodynamic principles to effectively choose and manipulate the relevant equations.
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(∂s/∂P) at constant volume =1/T ×(∂u/∂T)at constant volume × (∂T/∂P) at constant volume

s(P,v)
Tds= du +pdv
h= u + pv
h(P,v)
u(P,v)
or other formula?
How am I going to choose ? Please guide

Thank
 
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Outrageous said:
(∂s/∂P) at constant volume =1/T ×(∂u/∂T)at constant volume × (∂T/∂P) at constant volume

s(P,v)
Tds= du +pdv
h= u + pv
h(P,v)
u(P,v)
or other formula?
I'm not expert on gas theory, so I'll just treat this as an algebraic question.
Of those 'formulae', only two are equations. One of those two involves h, not mentioned anywhere else. So that leaves Tds= du +pdv as the only candidate.
What would the constant volume version of that equation look like?
 
haruspex said:
I'm not expert on gas theory, so I'll just treat this as an algebraic question.
Of those 'formulae', only two are equations. One of those two involves h, not mentioned anywhere else. So that leaves Tds= du +pdv as the only candidate.
What would the constant volume version of that equation look like?

The others also can become equation like s is function of v and p
So ∂s=(∂s/∂p)dp + (∂s/∂v)dv
Then h=u + pv , can be dh= du + Pdv + vdp
This is all just dealing with mathematics , please teach me how to choose
Do you mean why did I put constant volume there? It means by keeping volume constant then only differentiate.
Thank
 
Outrageous said:
(∂s/∂P) at constant volume =1/T ×(∂u/∂T)at constant volume × (∂T/∂P) at constant volume

s(P,v)
Tds= du +pdv
h= u + pv
h(P,v)
u(P,v)
or other formula?
How am I going to choose ? Please guide

Thank

Have you considered using the Maxwell relations?

BiP
 
Outrageous said:
Do you mean why did I put constant volume there?
No, I mean take this equation: Tds= du +pdv
and turn it into an equation involving partial derivatives, v being constant.
 
Bipolarity said:
Have you considered using the Maxwell relations?

BiP

haruspex said:
No, I mean take this equation: Tds= du +pdv
and turn it into an equation involving partial derivatives, v being constant.

I am not really understand what is Maxwell ,
I only can get (∂s/∂P) at constant volume = (1/T)(∂h/∂P)constant volume -(v/T)
 
Outrageous said:
I only can get (∂s/∂P) at constant volume = (1/T)(∂h/∂P)constant volume -(v/T)
Please post your working to get that.
 
Trial
 

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This first , only that second deriavative
 

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  • #10
You need to follow BiP's advice and familurize yourself with the derivation and application of the Maxwell equations.
 
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