Macrostates and microstates | Thermodynamics | Physics | Khan Academy

TL;DR

There is a distinction between macrostates, which describe the properties of a system, and microstates, which describe the individual properties of particles within the system.

Transcript

SAL: I've done a bunch of videos where I use words like pressure and-- let me write these down-- pressure and temperature and volume. And I've done them in the chemistry and physics playlist. Especially the physics playlist, but even in the chemistry playlist, I also use words like kinetic energy. I'll just write e for energy. Or I use force and ve... Read More

Key Insights

• ❓ Macrostates describe the overall behavior of a system, while microstates describe the individual properties of particles within the system.
• 💱 Macrostates are well-defined when the system is in thermodynamic equilibrium, while microstates are constantly changing.
• ❓ Macrostates can be determined by analyzing the collective properties of microstates.
• 🥵 The distinction between macrostates and microstates is important in understanding thermodynamics and how heat moves within a system.
• 🫀 Although macrostates were devised before the understanding of atoms and molecules, they can still be applied to describe the behavior of systems at the macroscopic level.
• ❓ Microstates provide a more detailed understanding of the behavior of individual particles within a system.
• 🚱 The transition between macrostates involves a period of non-equilibrium where macrostate properties are not well-defined.

Questions & Answers

Q: What are macrostates and microstates?

Macrostates are properties of a system that describe its overall behavior, while microstates describe the specific properties of individual particles within the system.

Q: How do macrostates and microstates relate to each other?

Macrostates are determined by the collective properties of microstates. The behavior and properties of the system as a whole can be understood by analyzing the individual properties of its constituent particles.

Q: When are macrostates well-defined?

Macrostates are well-defined when the system is in thermodynamic equilibrium. This means that the pressure, temperature, and volume of the system are constant and not changing over time.

Q: Do microstates change in equilibrium?

Yes, microstates continuously change, even in equilibrium. Individual particles within the system are constantly interacting and exchanging momentum and energy, leading to changes in their specific properties.

Summary & Key Takeaways

• Macrostates are properties of a system, such as pressure, temperature, and volume, that describe the overall behavior of the system.

• Microstates are specific properties of individual particles within the system, including their momentum, position, and kinetic energy.

• Macrostates are well-defined when the system is in thermodynamic equilibrium, while microstates are constantly changing even in equilibrium.