The pressure, volume and temperature of a gas are closely related to the motion and collisions of its particles.
This interactive PhET simulation allows you to investigate how changing temperature, volume and the number of gas particles affects the pressure of a gas, while also observing what is happening at the particle level.
Make predictions before changing the conditions. Compress the gas, heat or cool it, and change the number of particles. Then use the movement and collisions of the particles to explain the changes you observe in pressure, volume and temperature.
Gas Properties is provided by PhET Interactive Simulations, University of Colorado Boulder, and is used under the CC BY-NC 4.0 licence.
1. Compress the gas
Keep the temperature and number of particles constant, then reduce the volume. Predict what will happen to the pressure. Use the particle collisions to explain your result.
2. Expand the gas
Increase the volume while keeping the temperature constant. What happens to the pressure, and why?
3. Heat the gas
Keep the volume fixed and increase the temperature. Observe the particle motion. How does the pressure change?
4. Cool the gas
Lower the temperature at constant volume. What happens to the speed of the particles and the pressure?
5. Add more particles
Keep the volume and temperature constant, then add more gas particles. Predict the effect on pressure before checking.
6. Connect pressure to collisions
Compare a high-pressure situation with a low-pressure one. What has changed about the frequency and force of collisions with the container walls?
7. Test the gas laws
Try to create conditions that illustrate:
For each one, decide which variable must be kept constant.
Keep asking:
How do changes in particle motion and collision frequency explain the behaviour of gases?