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So for a reversible process, the entropy is conserved for both the system and the surroundings (but not for each of them individually)?BvU said:
Thank you so much!BvU said:
For the gas it is clear that the entropy is constant only during the adiabatic transformation. However I am not sure how can I calculate the entropy of the surroundingsBvU said:
No, sorry. I meant in the other 2 cases the isothermal and constant volume. How can I know that the change in entropy of the system exactly compensate the one of the surrounding? It is just by the definition of reversible process or there is something more to it?BvU said:
More through energy conservation plus ##dQ = TdS##.Silviu said:
For a reversible process, when heat is transferred, the temperature difference between the gas and its surroundings is infinitesimal. There has to be some difference in temperature, otherwise heat won't flow, but since the two are essentially at the same temperature, the decrease in entropy of one is equal to the increase of the other.Silviu said:
Entropy is a measure of disorder or randomness in a system. In the context of the GRE question, it refers to the amount of disorder in a given chemical reaction or physical process.
The second law of thermodynamics states that the total entropy of a closed system (one that does not exchange matter or energy with its surroundings) will always increase over time. This means that as a system becomes more disordered, its entropy increases.
The change in entropy of a system can be calculated using the equation ΔS = Q/T, where ΔS is the change in entropy, Q is the amount of heat transferred, and T is the temperature in Kelvin. Entropy is measured in units of joules per Kelvin (J/K).
In general, chemical reactions that result in an increase in entropy are more likely to be spontaneous, while those that result in a decrease in entropy are less likely to be spontaneous. This is because increasing entropy leads to a more disordered state, which is favored by the second law of thermodynamics.
In addition to considering the change in enthalpy (ΔH) and temperature (ΔT), the change in entropy (ΔS) can also be used to predict the direction of a chemical reaction. If ΔS is positive, the reaction is more likely to be spontaneous in the forward direction. However, if ΔS is negative, the reaction is more likely to be spontaneous in the reverse direction.
