States of Matter: Kinetic Molecular Theory of Gases

Key Concepts

Kinetic Theory: All particles of matter are in constant motion.
Kinetic Energy: Energy of motion.
Gas Behavior:
- Gases are composed of tiny particles with negligible volume.
- Particles do not attract or repel each other; they move independently.
- Gases expand to fill their container and have no definite volume.
- Particles move randomly and quickly (thousands of km/hr).
- Motion described as a "random walk," moving in straight lines until colliding.
- Collisions between particles are elastic (no energy loss).

Definition: Measure of collisions of gas particles with each other and container walls.
Factors Affecting Gas Pressure:
- Number of collisions increases pressure.
- More particles in a space and higher temperature increase pressure.
- Pressure in a vacuum (no collisions) is zero.

Popcorn Popping: Water vaporizes inside kernels, creating pressure from collisions, causing them to pop.
Peeps in a Vacuum:
- Demonstration of removing air pressure.
- Expanding marshmallows show the effect of decreased air pressure on gas-filled substances.

Definition: Caused by air in the atmosphere.
Impact of Altitude:
- Higher altitude results in lower atmospheric pressure.
- Less oxygen available; fewer collisions; lower pressure.

Units of Measurement:
- 1 atmosphere (atm)
- 760 mm of mercury (mm Hg)
- 101.3 kilopascals (kPa)
Measurement Tool: Barometer
- Measures atmospheric pressure by mercury level in a tube.

The kinetic molecular theory of gases explains their behavior and the factors that affect gas pressure. Understanding gas pressure is crucial for various applications and demonstrates the principles of particle motion and energy transfer without loss.