Internal energy vs. Enthelpy vs. Entropy

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The equations Q=m(u2-u1) + W and Q=m(h2-h1) serve different purposes in thermodynamics. The first equation accounts for changes in internal energy and work done, while the second focuses on enthalpy changes at constant pressure. The first equation is universally applicable, whereas the second is specifically used when pressure remains constant throughout the process. Understanding the context of the system is crucial for selecting the appropriate equation. Proper application ensures accurate calculations in thermodynamic scenarios.
ipocoyo
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What is the difference between Q=m(u2-u1) + W & Q=m(h2-h1)?

Basically I am trying to figure out 2 different sets of questions and apparently using these separate equations yield different answers, and I don't know which equation to use. From my understanding, both of them are used in closed systems and also when there is a constant pressure but a change in volume? So when exactly do I use which one?
 
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ipocoyo said:
What is the difference between Q=m(u2-u1) + W & Q=m(h2-h1)?

Basically I am trying to figure out 2 different sets of questions and apparently using these separate equations yield different answers, and I don't know which equation to use. From my understanding, both of them are used in closed systems and also when there is a constant pressure but a change in volume? So when exactly do I use which one?
The first equation is always true. The second equation applies when the pressure is constant during the process, and equal to the initial pressure of the gas.
 

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