Kinetic Theory
We are going to create a mathematical model for an ideal gas. We will use this model to explain and predict the bahaviour of real gases.
Imagine a ball bouncing around inside a box. In kinetic theory our model consists of a very large number of such balls bouncing around inside the box. The force they produce when they collide with the walls of the box results in the pressure of the gas.
The best models are simple so we are going to make some assumptions about our tiny particles (learn these)
They are perfectly elastic spheres
So they do not lose kinetic energy when they collide, otherwise they would slow
down
There is a very large number of them moving randomly
So there are equal numbers moving in all directions producing uniform pressure
They do not interact with each other, only with the walls of the container
The forces between the particles we assume can be ignored
The time for a collision is negligible compared to the time between
collisions
We us this when we calculate the force they produce on the walls
Without any mathematical analysis we can use this model to explain the gas laws qualitatively.
| The Pressure Law | Charles' Law | Boyle's Law |
| If we increase the temperature the balls whiz around faster. They hit the walls with more force, and more often, so the pressure increases. | Because the force on the piston increases it is pushed up so the volume increases until the pressure is balanced again. | If we make the volume of the container smaller then the particles hit the walls more often so the pressure increases. |