Question about thermodynamic quantities

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In constant pressure thermodynamic processes, dH equals dqp, raising questions about the necessity of reversible work, where dw may equal zero if dv is zero. The discussion also explores whether qv must be reversible heat transfer, particularly in the context of irreversible heat transfer. Additionally, the relationship dU equals dqv is examined for its dependence on reversibility. The impact of ideal versus non-ideal gases on these thermodynamic relations is highlighted, especially in scenarios like Joule's free expansion. Clarification is sought on how these factors influence thermodynamic behavior, particularly regarding the nature of reversible processes.
kelvin490
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We know that for constant pressure thermodynamic processes, dH=dqp. My question is, does it implies that only reversible work is possible in this processes so that dw=0 because dv is zero? In addition, does qv necessarily be reversible heat transfer in this case? What if the heat transfer is irreversible?

Similar question for dU=dqv, does the process need to be reversible?

Another question is, do the above relations have anything to do with whether or not the system is an ideal gas? I have heard from a lecture that du≠dqv in Joule's free expansion for non-ideal gas. Consider reversibility and whether it's ideal gas there are four combinations of situations (ideal gas reversible,ideal gas irreversible, non-ideal gas reversible, non-ideal gas irreversible). I get confused with how these factors affect the thermodynamic relations.
 
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Is it true that reversible process can only occur in the form of infinitesimal expansion/compression?
 

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