Heat transaction of a non-ideal gas

AI Thread Summary
The discussion focuses on calculating heat interactions for non-ideal gases during isobaric and isochoric processes. It emphasizes the importance of internal energy (U) and enthalpy in relation to temperature and volume or pressure. Participants question the use of heat capacities as functions of temperature and pressure and discuss the necessity of specific parameters for actual gases like nitrogen instead of general formulas. A reference to a relevant paper is provided, although access issues are noted, suggesting that alternative resources should be sought. The conversation concludes with a commonly used equation for changes in internal energy in thermodynamics.
Uthpala Kaushalya
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Here I want to know how to find the heat interactions of non-ideal gases in the following processes.
1. Isobaric process
2. Isochoric process

I know that internal energy U depends on temperature and volume. And the enthalpy depends on temperature and pressure.
How calculation of heat transaction can be calculated? and what's the connection between following taylor series expansion with calculating the heat interaction.

U(T,V)
U(T+T, V+V) = U(T,V) + ∂u/∂ t |v * T + ∂u/∂v |T * V + Higher Terms
 
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Why don't use the heat capacities of the gases, as functions of T and P?
Are talking about actual gases or just about a model of non-ideal gas (like Van der Waals)?
If it's a specific gas (like nitrogen) you may need to find some actual values of parameters for that gas rather than using a general formula.
Here is a paper that may help.
http://journals.aps.org/pr/pdf/10.1103/PhysRev.34.1615
 
Last edited by a moderator:
You would like to have an equation for calculating the changes internal energy with changes in temperature and volume for a non-ideal gas. Is that correct? In this equation, you would like everything expressed in terms of known functions like heat capacity and p-v-T behavior?
 
Chestermiller said:
You would like to have an equation for calculating the changes internal energy with changes in temperature and volume for a non-ideal gas. Is that correct? In this equation, you would like everything expressed in terms of known functions like heat capacity and p-v-T behavior?
Yes :)
 
nasu said:
Why don't use the heat capacities of the gases, as functions of T and P?
Are talking about actual gases or just about a model of non-ideal gas (like Van der Waals)?
If it's a specific gas (like nitrogen) you may need to find some actual values of parameters for that gas rather than using a general formula.
Here is a paper that may help.
http://journals.aps.org/pr/pdf/10.1103/PhysRev.34.1615
This article cannot be read. Should I buy this?
 
Last edited by a moderator:
No, you should be able to find other articles that have free access. I don't think this is a very rare topic.
 
The following equation is in every thermo book:
$$dU=C_vdT-\left[P-T\left(\frac{\partial P}{\partial T}\right)_V\right]dV$$
 

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