This sealed box contains 10 molecules of helium. Start the clock and watch what happens to the molecules of gas as they move inside the box. Observe how many times the molecules collide with the walls of the box and the pressure these collisions produce. Then press the right arrow to continue.

Molecules of a gas are in continuous chaotic motion. Therefore, some random collisions between molecules will occur in an enclosed space. In this model, such collisions do not affect pressure, which is created by gas molecules colliding with the walls of the container.