The discussion clarifies that the thermodynamic explanation of irreversibility encompasses both macroscopic and microscopic viewpoints. It establishes that irreversibility is fundamentally a macroscopic concept, as it relates to large-scale properties like pressure and temperature, which do not apply at the molecular level. The expansion of an ideal gas and the melting of ice are cited as examples illustrating this dual perspective. Ultimately, all real processes exhibit some degree of irreversibility, contrasting with the theoretical notion of reversibility.
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erty said:The thermodynamic explanation of irreversibility - does it include the microscopic view of a process, i.e. the expansion of a ideal gas (the random movement of the molecules) or the melting of an ice cube?
Or is it only defined within the macroscopic world?
Irreversibility, of course, is the opposite of reversibility. A reversible process is one that can change direction with an infinitessimal change in conditions. In reality, all processes are somewhat irreversible. An example would be the expansion of a gas caused by applying a pressure to a container wall that was infinitessimally lower than the pressure of the gas. An infinitessimal increase in pressure will reverse the expansion and result in a compression of the gas.erty said:The thermodynamic explanation of irreversibility - does it include the microscopic view of a process, i.e. the expansion of a ideal gas (the random movement of the molecules) or the melting of an ice cube?
Or is it only defined within the macroscopic world?
Andrew Mason said:In thermodynamics, reversibility is definitely a macroscopic concept. It has no meaning at the molecular level. Pressure and temperature are macroscopic concepts that relate to qualities of large numbers of molecules and are not defined at the molecular level.
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