Reversibility

A reversible process is one that proceeds slowly enough to remain in equilibrium throughout the process.
For irreversible or non-equilibrium processes it is important to use the external pressure to calculate the PV work.

[@cookiemaria780]

Really helpful video! Thank you so much for all your physical chemistry videos, they help so much for university!!

[@PhysicalChemistry]

Great, that's good to hear. Thanks for the comment

[@hamdanabdulla8507]

Thank u So much

[@PhysicalChemistry]

You're very welcome

[@beasthunter3302]

Is the microscopic pressure of each state different ?

[@PhysicalChemistry]

Yes! The microscopic pressure is −∂Eᵢ/dV. Since Eᵢ is different for each state of a 3d PIB, the microscopic pressure turns out to be different as well.