In this section you will find background information on the Ideal Gas Law.

Imagine a piston that moves freely inside a cylinder as changes occur to the gas trapped in the lefthand side of the cylinder pictured below. Suppose we speed up (increase the velocity) of the gas particles in the cylinder on the left. The number of particles and the pressure is held constant. What happens?

Particles speed up. The volume increases.

Figure 1. An example of Ideal gas law.

This is analogous to taking an air filled balloon from a cold room into a very warm room; the balloon expands to accommodate the faster movement of particles that results when the temperature increases.


What is an Ideal Gas?
An ideal gas or perfect gas is one which obeys Boyle's Law and Charles' Law exactly. An ideal gas obeys the Ideal Gas Laws.

What is the Ideal Gas Law?
The ideal gas law is the equation of state of a hypothetical ideal gas.

PV=nRT=NkT

where P is the absolute pressure, V is the volume of the vessel, n is the number of moles of a gas, R is the universal gas constant = 8.3145 J/mol K, T is the absolute temperature, N is the number of molecules, k is the Boltzmann constant = 1.38066 x 10-23 J/K = 8.617385 x 10-5 eV/K.

The ideal gas is modeled on the kinetic theory of gases which has four basic postulates:
1. Gases consist of small particles (molecules) which are in continuous random motion.
2. The volume of the molecules present is negligible compared to the total volume occupied by the gas.
3. Intermolecular forces are negligible
4. Pressure is due to the gas molecules colliding with the walls of the container.

Source:
http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/idegas.html
http://www.ausetute.com.au/idealgas.html