1What causes gas pressure
Gas particles hit the walls of their container. Every hit is a tiny push, and billions of hits make gas pressure.
gas pressurecollision
Lesson 2.3 notes
Gas pressure
Gas particles hit the walls of their container. Every hit is a push, and together they make gas pressure.
2Less space, more pressure
Squash a gas into a smaller volume and its particles hit the walls more often, so the pressure rises.
volume
3Hotter gas, more pressure
Heating makes gas particles move faster. They hit the walls harder and more often, so the pressure rises.
temperature
4More particles, more pressure
Pumping air into a tyre adds particles. More particles means more hits, so the pressure rises.
pump
5Air pressure
The weight of the air above us causes air pressure. Higher up there is less air above, so the pressure is lower.
atmospheric pressure
6The collapsing can
When the steam in a sealed can condenses, few gas particles are left inside. The air outside pushes harder and crushes the can.
pressure difference
Explore: Pressure lab
Change the volume and the temperature, and watch the pressure gauge.
Common mistake: Squashing a gas doesn't squash the particles
The particles stay exactly the same size. Squashing a gas pushes them closer together, so there is less empty space between them.
Remember
- Gas pressure is caused by particles hitting the walls of their container.
- A smaller volume, a higher temperature or more particles means more hits, so a higher pressure.
- Air pressure comes from the weight of the air above us, and is lower higher up.
Going further at GCSE
GCSE: Gas temperature and pressure → GCSE: Internal energy and temperature →