Can someone explain this thermodynamics related doubt i have?

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In the discussion, two thermodynamic scenarios involving a piston-cylinder arrangement are analyzed. The first scenario involves adding heat at constant volume, leading to a temperature and pressure rise, followed by an adiabatic expansion to the initial pressure. The second scenario adds heat at constant pressure, resulting in expansion and a change in internal energy. The key question posed is whether these two scenarios are equivalent regarding changes in internal energy, work done, and final volume expansion. Participants suggest performing calculations to clarify the outcomes of each scenario.
lawofnature
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Assume a piston cylinder arrangement. External pressure always equals internal pressure ( reversible conditions ). Now consider these two scenarios:

Scenario one: q heat is suddenly added to the arrangement causing a temperature rise and consequently pressure rise, but the volume is yet constant. That implies:
q = n Cv dT
Now let's decrease the pressure adiabatically to initial pressure p1 (before temp. rise). There will be adiabatic work done in expanding to lower pressure at the cost of internal energy:
p dV = n Cv dT

Scenario two: q heat is added at a constant pressure p1 (isobaric process) causing expansion and change in internal energy.

Are the two scenarios equivalent in terms of change in internal energy, work done and final expansion (of volume)?
 
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lawofnature said:
Assume a piston cylinder arrangement. External pressure always equals internal pressure ( reversible conditions ). Now consider these two scenarios:

Scenario one: q heat is suddenly added to the arrangement causing a temperature rise and consequently pressure rise, but the volume is yet constant. That implies:
q = n Cv dT
Now let's decrease the pressure adiabatically to initial pressure p1 (before temp. rise). There will be adiabatic work done in expanding to lower pressure at the cost of internal energy:
p dV = n Cv dT

Scenario two: q heat is added at a constant pressure p1 (isobaric process) causing expansion and change in internal energy.

Are the two scenarios equivalent in terms of change in internal energy, work done and final expansion (of volume)?
Why don't you just run the calculations as see for yourself what happens (rather than guessing)?

Chet
 
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