Kinetic Molecular Theory (KMT)

Kinetic Molecular Theory of gases attempts to explain the properties of gases such as pressure, temperature, or volume, by looking at what they are made up of and how they move

Kinetic refers to motion

The energy an object has because of its motion is called kinetic energy

Example:   A ball rolling down a hill has kinetic energy

Main Components of KMT:

There are three main components to kinetic theory:

1. Perfectly elastic collisions, no energy is gained or lost when gas molecules collide
2. Gas molecules take up no space they are so small
3. Gas molecules are in constant, linear, random motion

 

How does Kinetic Theory explain Gas Pressure?

 

Gas Pressure results from fast moving gas particles colliding with the sides of a container

More Collisions = Higher Pressure

 

How does Temperature relate to Kinetic Theory?

 

Temperature is a measure of the average kinetic energy of all the particles in a gas

Higher Energy = Higher Temperature

 

Laws Developed from KMT:

Through KMT, several Laws were developed to help calculate the changes in pressure, temperature, and volume of gases.

There are 6 Basic Laws:

                1. Boyle’s Law

                2. Charles’ Law

                3. Gay-Lussac’s Law

                4.  Avogadro’s Law

                5. Ideal Gas Law – volume liters only

                6. Dalton’s Law

 

These are the Gas Law's, for their detail learning you can see What are Gas Law's and How are Gas Laws used in real Life.

Boyle’s Law

 

Boyle’s Law – at constant temperature, the volume of the gas increases as the pressure decreases. (and the volume of the gas decreases and the pressure increases).  They are inversely related.

P₁V₁ = P₂V₂

 

Charles’ Law

 

Charles’ Law – at a constant pressure, the volume of a gas increases as the temperature of the gas increases (and the volume decreases when the temperature decreases).  They are directly related.

V₁ / T_{1 =} V2 / T2

 

Combined Gas Law

 

A combination of Boyle’s, Charles’, and Gay-Lussac’s Laws

P₁ V₁ / T_{1 =}  P₂V₂ / T₂

 

Gay-Lussac’s Law

Gay-Lussac’s Law – at a constant volume, the pressure of a gas increases as the temperature of the gas increases (and the pressure decreases when the temperature decreases).  They are directly related.