Kinetic theory model
Gas particles are constantly moving in all directions. However, we cannot observe these gases because they are very small. The “Kinetic theory model” can replace these invisible gas particles with beads and make them visible.
Metaphor of “Kinetic theory model”
- As the motor speed increases, the movement of the beads becomes more active. This is similar to the movement of gas particles becoming more active as the temperature increases.
- The beads pushing up on the upper piston are likened to the pressure of a gas.
- Beads can only repel each other when they collide but cannot attract each other. Similarly, ideal gas particles can only repel each other when they collide but cannot attract each other.
- There is a lot of empty space between the actively moving beads. Thus, the volume of a gas is the size of the space occupied by the gas, not the size of the gas particles.
- As the beads’ motion becomes more active, the space they occupy increases. This can be likened to the volume of a gas increasing as its temperature increases.
Disadvantages of the “Kinetic theory model”
The “Kinetic theory model” cannot wholly describe gas particles. While gas particles collide perfectly elastically with the walls of the container, the speed of the beads gradually decreases as they collide inelastically with the walls of the container. Therefore, a motor is installed at the bottom of the device to supplement the decreasing kinetic energy.
It seems like the motor’s rotation speed and volume are not proportional.
When the pressure of the gas is constant, the volume of an ideal gas is proportional to its temperature. The temperature of the gas is proportional to the kinetic energy of the gas particles, and the kinetic energy of the particles is proportional to the square of their speed. Therefore, the particles’ speed and volume are not proportional. In other words, the volume of the gas is proportional to the square of the speed of the particles. Please explore the detailed reason yourself.