Chemical Engineering Thermodynamics Section Association 2-14
Thread Content
Regarding reversible and irreversible processes, which of the following statements is correct? 1. A process that involves heat generation due to friction can be considered a reversible process. 2. All actual adiabatic processes are reversible processes. 3. The greater the irreversibility of a process, the more work is lost. 4. All irreversible processes result in an increase in the entropy of the surroundings. What I want to ask is how to analyze the fourth option: how can we determine whether the entropy of the surroundings and that of the system increases or decreases when the increase in the system’s entropy is greater than zero? ? ? Thank you
@zhanghp30 @higee Expert, please advise on how to determine the entropy increase of the isolation system, as well as the entropy changes of the system and the environment. Thank you
Thank you for your trust. To be honest, thermodynamics is also a real headache for me. Let me share some personal views. When considering the system and the environment as isolated systems, an irreversible process is necessarily one in which entropy increases, that is, ΔS_system + ΔS_environment > 0. For the environment, ΔS_environment equals the heat transferred between the environment and the system divided by the environment’s temperature
What is the entropy change of that system? What corresponds to environmental entropy change? ?
Firstly, entropy is a quantity that indicates the degree of disorder within a system or environment; in other words, the greater the motion of the molecules inside, the higher the entropy. Since the motion of molecules is related to temperature, it can be concluded that as temperature increases, the entropy of the environment or system also increases. This is my personal understanding
Furthermore, since molecular motion always exists in any substance and under any condition, entropy is always greater than 0
What about the fourth option? ?
Isn’t it the system that does work on the environment?
The fourth option is wrong; I can only see that the entropy change of the isolated system is greater than zero. How can one determine that the entropy change of the environment might also be less than zero?
This post was last edited by Higee on 2016-6-4 at 18:53. If the system and its environment are considered as an isolated system, it can be regarded as adiabatic. The total entropy change is either zero (for reversible processes) or greater than zero (for irreversible processes). The entropy change of the system can be determined based on the changes in the system’s state