Enthelpy so commonly described only in constant pressure situations?

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Enthalpy is primarily described in constant pressure situations because it simplifies calculations and enhances readability in thermodynamics. While it can be applied to varying pressure environments, doing so complicates the equations, requiring additional considerations for pressure changes. The use of enthalpy allows for a straightforward accounting of work and heat under constant pressure. In contrast, when pressure varies, the analysis becomes more complex, necessitating the inclusion of pressure effects alongside heat and work. Overall, the preference for constant pressure scenarios in enthalpy discussions stems from the desire for simplicity and clarity in thermodynamic equations.
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Why is enthalpy so commonly described only in constant pressure situations? It applies to change in pressure environments as well.
 
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It is just a matter of taste: choosing what makes a balance simple or choosing to write a little longer balance equation.

The enthalpy can be related to other thermodynamic potentials.
It was probably defined to make things simpler. Try to re-write all the thermodynamics without the enthalpy or without the Gibbs free energy, you will see that some chapters will grow in page number and will be much less readable. That's all, I think.

When pressure is kept constant, work or heat can be accounted directly in terms of enthaply variations.
If pressure is not kept constant, you can still use enthalpy in the accounting but you will need to include not only the effect of work or heat but also the effect of pressure variation.
 
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