ThermodynamicsLesson 1 of 7 in the course The Second Law of Thermodynamics

Reversibility, Free Expansion, and Common Thermodynamic Processes

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

A process may change a system while also affecting its surroundings. This lesson distinguishes reversible processes from irreversible ones and uses the free expansion of an ideal gas to explain why restoring a system alone is not enough.

A reversible process is an idealized process that can be reversed so that both the system and its environment return exactly to their initial states. It is not enough to restore only the system: the surroundings must also be restored without leaving any lasting change.

All flashcards

Reversible process
An idealized process that can be reversed so both the system and its environment return exactly to their initial states.
Quasi-static process
A process that proceeds through states arbitrarily close to equilibrium.
Clausius statement
Heat does not flow spontaneously from a colder object to a hotter one.
Free expansion
Expansion into a vacuum, where the gas does no work on an opposing force.
Adiabatic process
A process in which no heat is transferred.

Quiz questions

  1. What must return to its original state for a process to be reversible?Answer: Both the system and its environment must return to their initial states.
  2. Why is quasi-static behavior necessary for reversibility?Answer: It lets the system pass through states arbitrarily close to equilibrium.
  3. During insulated free expansion of an ideal gas into a vacuum, what are the heat transfer and work done by the gas?Answer: Q=0Q=0 and W=0W=0.
  4. According to the Clausius statement, which heat transfer cannot occur spontaneously?Answer: Heat transfer from a colder object to a hotter object.
  5. For a gas undergoing an isobaric process, what expression gives the work done by the gas?Answer: W=pΔVW=p\Delta V

Based on University Physics Volume 2 by Samuel J. Ling, William Moebs, Jeff Sanny (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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