Entropy State Variable: Thermal Equilibrium Questions

In summary, the conversation discusses a closed system of Ideal Gas with fixed volume and mol volume, in thermal equilibrium with its surroundings at room temperature. The system is cooled and then re-heated until it reaches thermal equilibrium again. The question is whether the entropy of the system has increased during this process and if the system is in equilibrium. The experts agree that the entropy remains constant and the system is in internal equilibrium. They also state that the way energy is added to the system is not relevant for the system itself, but may be relevant when considering the system and its environment together.
  • #1
TomWhite87
1
0
I have a few questions about entropy and path
Scenario
I have a closed system of Ideal Gas- Volume is Fixed , Mol Vol is fixed.
At room temperature the system is in thermal equilibrium with its surroundings
I then cool this system removing Q .
To this system I then re-add Q until it is again in thermal equilibrium at room temperature.
At all points of this process within this system, all subsets of the gas have an equal distribution of energy and mass

In this process have I increased the entropy of the System since the end state is equal to the beginning
and
Is the system in equilibrium as energy and mass cannot be dispersed further ?
Is how I added the energy to the system (the path) ever relevant ?
 
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  • #2
TomWhite87 said:
In this process have I increased the entropy of the System since the end state is equal to the beginning
I guess you mean you have not increased the entropy of the system.

TomWhite87 said:
Is the system in equilibrium as energy and mass cannot be dispersed further ?
What equilibrium are you talking about? If you are talking about internal equilibrium, you have stated that it is maintained by construction.

TomWhite87 said:
Is how I added the energy to the system (the path) ever relevant ?
With respect to the system, I would say no. Since the volume is fixed, there is no work involved, hence only an exchange of energy. If you consider the system plus the environment, then yes, the way you remove the energy and put it back in will be relevant.
 
  • #3
TomWhite87 said:
Is how I added the energy to the system (the path) ever relevant ?
To expand on what Dr. Claude said, as far as the system is concerned, the entropy is an equilibrium physical property of the material comprising the system, so between an initial thermodynamic equilibrium state and a final thermodynamic equilibrium state, the change in its entropy is independent of the path at took it between the two thermodynamic equilibrium states.

Chet
 

1. What is entropy and how is it related to thermal equilibrium?

Entropy is a measure of the disorder or randomness in a system. In thermal equilibrium, the system has reached a state of maximum entropy, where there is no net flow of heat and the system is at a uniform temperature.

2. How is the entropy state variable defined?

The entropy state variable is defined as the amount of thermal energy in a system that is unavailable to do work. It is denoted by the symbol S and is measured in units of joules per kelvin (J/K).

3. What is the relationship between entropy and temperature in thermal equilibrium?

In thermal equilibrium, the entropy of a system is directly proportional to its temperature. This means that as the temperature increases, so does the entropy. When a system reaches thermal equilibrium, the entropy and temperature remain constant.

4. Can the entropy of a system be decreased?

According to the second law of thermodynamics, the total entropy of a closed system cannot decrease over time. However, the entropy of a specific part of the system can decrease if energy is transferred out of that part, resulting in an increase in entropy in another part of the system.

5. How does entropy relate to the arrow of time?

The increase of entropy with time is often referred to as the "arrow of time". This is because in natural processes, entropy tends to increase, meaning that systems move towards states of higher disorder. This is consistent with the fact that time only moves in one direction, from past to future.

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