Kinetic Molecular Theory II

The kinetic molecular theory assumes that:

1. Every substance is made up of tiny particles called molecules.

2. The molecules are in constant random motion, colliding elastically with one another and changing their direction.

3. There is always an attractive force between the molecules.

4. The volume of the gas molecules is negligible compared to the volume of the gas container.

Kinetic Theory: Explanation of Temperature Increase:

Molecules of a substance are in constant motion, hence they possess kinetic energyEnergy is the ability to do work. Energy exists in several forms such as heat, kinetic or mechanical energy, light, potential energy, and electrical energy. Units of Energy: The SI unit... More. When heat is added to a substance, it causes an increase in the speed of motion of the molecules of the substance and this leads to an increase in kinetic energy of the molecules of the substance and an increase in temperature of the substance.

Using the Kinetic Molecular Theory to Explain Expansion, Melting and Evaporation:

When heat is added to a substance, molecules in the substance experience an increase in kinetic energy, vibrate strongly, break away from the intermolecular force of attraction that holds the molecules together, and move further apart. Depending on the substance and the amount of heat added, the movement can cause:

• the object to expand.
• the substance to melt or change from a solid-state to a liquid state.
• the substance to change to vapour.