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Apoorv3012
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What is enthalpy of a system based on macroscopic POV of thermodynamics and not chemistry? And how do we use it to calculate the total heat transfer in isentropic processes?
This is incorrect. In a reversible Carnot cycle, which is an isentropic process, the change in enthalpy is zero, and the work is equal to the net heat transferred. Even for an isentropic reversible single-step change for a closed system, it is the internal energy which is equal to minus the work done on the surroundings, not the enthalpy.stockzahn said:Enthalpy H is the sum of the internal energy U and the flow work p⋅V.
H = U + p⋅V
In an isentropic process no heat is transferred, the enthalpy difference of the fluid corrisponds to the work performed by/on the fluid.
Yes, sorry I forgot to add that.Chestermiller said:Apoorv312: Are you asking about an open system operating at steady state when you ask "how do we use it to calculate the total heat transfer in isentropic processes?"
Thank you sir, that really helped.Chestermiller said:For a flow system like the one described, you first follow each little parcel of gas going through the system, and treat it as a closed system that is subjected to an adiabatic reversible expansion to the final pressure exiting your device. On this basis, you determine the temperature change for each of the parcels. This will determine the exit temperature from your flow system. The change in enthalpy per unit mass flowing through your system is then equal to Cp times the temperature change.
Chet
Enthalpy is a thermodynamic property that represents the total energy of a system, including its internal energy and the work required to change its volume or pressure.
Enthalpy is related to heat and work through the first law of thermodynamics, which states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system.
Enthalpy takes into account the internal energy of a system as well as the work required to change its volume or pressure, while internal energy only represents the total energy of the system.
Enthalpy is used to study the overall energy changes of a system during chemical or physical processes, such as reactions or phase transitions. It allows us to analyze and predict the behavior of a system under different conditions.
Enthalpy is significant in chemical reactions as it helps us understand the energy changes that occur during a reaction. It allows us to determine whether a reaction is exothermic (releases heat) or endothermic (absorbs heat) and to calculate the amount of heat involved.