Basic Physical Picture of a Gas
To understand the physical properties of a gas from microscopics, we
employ the following idealized yet accurate kinetic description that contains
the following elements:
In terms of this cartoon-like picture, we can understand many fundamental
properties of real gases.
- Gas molecules (or atoms) are structureless.
- Molecules move freely between collisions.
- Collisions occur occasionally (relatively).
- Collisions are nearly instantaneous and elastic.
- Molecular velocities are randomized upon each collision.
- Molecular speeds are distributed over a moderate range.
- The typical speed is set by the temperature.