Difference between enthelphy and heat?

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SUMMARY

The discussion clarifies the distinction between enthalpy and heat in thermodynamics. Enthalpy is defined as the sum of internal energy (U) and the product of pressure (P) and volume (V), represented by the equation H = U + PV. In processes involving heat transfer, such as flow through a pipe, the heat added or removed corresponds to the change in enthalpy. Conversely, in a sealed container, the heat change reflects the change in internal energy, emphasizing that heat is a transport phenomenon rather than a property of a substance.

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  • Understanding of thermodynamic principles
  • Familiarity with the concepts of internal energy and enthalpy
  • Knowledge of heat transfer mechanisms
  • Basic grasp of pressure-volume work in thermodynamic systems
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  • Explore the concept of heat capacity and its relation to enthalpy
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asdf1
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in my thermodynamics textbook, enthalphy=U+PV
and (delta)heat=(delta)U+(delta)PV
those 2 look the same...
can anybody explain the difference?
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Hi asdf1. Take a look at your book again, I think you've taken it out of context. For example, flow through a pipe where heat is added or removed between two points in the pipe is a process in which the heat added/removed is equal to the enthalpy change in the fluid. On the other hand, for the situation where heat is added to a sealed container (ex: a pressurized tank), the amount of heat added or removed is equal to the change in the fluid's internal energy.
 
I was taught that enthalpy was a property of a substance. Heat is a transport phenomenon only (i.e. transfer of energy) and that there is no such property as heat.
 
at constant pressure with only expansion work the enthalpy of the substance does equal to the heat pertaining to the situation, that is q_p
 
thanks! :)
 

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