9.1 Kinetic Molecular Theory
Notes
The kinetic molecular theory (KMT) explains how gases behave using a model of moving particles.
- Gas particles are tiny and far apart; their own volume is very small compared with the container.
- They move in constant, random, straight-line motion.
- Collisions are elastic: no kinetic energy is lost overall.
- There are no attractive or repulsive forces between particles.
- The average kinetic energy is proportional to the Kelvin temperature. Hotter gas means faster particles.
- Gases that follow these rules are ideal gases. Real gases act most ideally at high temperature and low pressure.
Practice
According to KMT, what happens to gas particles when temperature increases?
Average kinetic energy is proportional to Kelvin temperature, so particles move faster.
Which assumption of KMT explains why gases are easy to compress?
Lots of empty space lets the particles be pushed closer together.
Real gases behave most like ideal gases at:
Fast, far-apart particles feel little attraction and their own volume matters little.
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