Kinetic Molecular Theory

Definitions

• Kinetic energy: the energy an object has because of its motion

• Kinetic molecular theory: states that all matter consists of tiny particles that are in constant motion

The Five Postulates

1. The particles in a gas are considered to be small, hard spheres with an insignificant volume.–The distance between particles in a gas

is larger than the distance between particles in a solid or liquid. –There is only empty space between the

particles.

Postulate 2

•2. No attractive or repulsive forces exist between the particles of a gas.

Postulate 3

3. The motion of the particles in a gas is rapid, constant, and random.– Gases fill their containers regardless of shape and

volume. – The particles travel in straight-line paths until they

collide with another particle or another object, such as the wall of their container.

– Their path of uninterrupted travel in a straight line is very short.

Postulate 4

4. All collisions between particles in a gas are perfectly elastic.– During an elastic collision, kinetic energy is

transferred without loss from one particle to another, and the total kinetic energy remains constant.

Postulate 5

5. The Kelvin temperature of a substance is directly proportional to the average kinetic energy of the particles of the substance.

Movie

• http://www.youtube.com/watch?v=_rsqBNhFG1Y

Worksheet

• Answer the questions from the worksheet in your spiral.