Entropy & Work Done: Understanding Reversible Heating/Stirring

In summary, the conversation discusses the change in entropy of a system in two different scenarios - stirring and reversible heating. It is argued that since entropy is a state function, there will be a change in entropy even during stirring, despite no heat transfer. This is in line with the second law of thermodynamics, which states that the change in the system and surrounding is zero in a reversible process. The understanding is that a change in temperature will always result in a change in entropy.
  • #1
pukb
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There is a container containing water (state 1) which is being stirred. There is a temperature rise (state 2) due to stirring. It is required to find out change in entropy of the system if the process is reversible. Since, there is no heat transfer there would be no change in entropy due to external work. But the argument is, if the same state (state 2) is reached by reversible heating of the fluid instead of stirring, there would be some change in entropy. Since entropy is a state function, it would mean that there is a change in entropy while stirring also.
How does one understand this?
 
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  • #2
( in my opinion ) whenever, there is a change in temperature, there will be a change in entropy.

The second low of thermodynamics, says it's right that the change of the system and the surrounding is zero only because it's a reversible process (ideal).

Sorry for my poor English.
 

1. What is entropy?

Entropy is a measure of the disorder or randomness in a system. It is a thermodynamic property that describes the distribution of energy in a system. In simple terms, it is a measure of the system's tendency to move towards a state of equilibrium.

2. How is entropy related to work done?

In thermodynamics, work is defined as the transfer of energy from one system to another. When work is done on a system, its entropy decreases. This is because the energy transferred is used to increase the order or decrease the randomness within the system.

3. What is reversible heating/stirring?

Reversible heating/stirring refers to a process in which the system is brought back to its original state after undergoing changes. This means that the entropy of the system remains constant throughout the process, as the system is able to return to its original state without any loss of energy. This is an idealized process that is used in thermodynamics to simplify calculations.

4. How is reversible heating/stirring different from irreversible heating/stirring?

In irreversible heating/stirring, the system undergoes changes that cannot be reversed. This means that the entropy of the system increases, as the system moves further away from its initial state. In contrast, reversible heating/stirring maintains a constant entropy throughout the process, with the system always able to return to its original state.

5. How is understanding reversible heating/stirring important in thermodynamics?

Understanding reversible heating/stirring is crucial in thermodynamics as it allows us to make accurate calculations and predictions about the behavior of systems. It also helps us to understand the relationship between entropy and work, and how different processes can affect the energy distribution within a system. Additionally, reversible processes are used as a basis for comparison to evaluate the efficiency of real-life processes, such as engines.

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