STUDENT SPACE · TOPIC 4
Gas pressure and Brownian motion
Explain gas pressure under controlled conditions and distinguish Brownian motion from molecular motion.
The essentials
- Gas pressure results from particles colliding with container walls.
- At constant volume, heating a fixed amount of gas increases pressure: particles move faster and collisions are more frequent and forceful.
- At constant temperature, reducing the volume of a fixed amount of gas increases the frequency of collisions with the walls.
- Brownian motion is the irregular movement of visible particles caused by uneven collisions with much smaller, moving particles.
Key vocabulary
| English | Chinese |
|---|---|
| pressure | 压强 |
| collision | 碰撞 |
| fixed volume | 固定体积 |
| compression | 压缩 |
| Brownian motion | 布朗运动 |
| suspended particle | 悬浮颗粒 |
Quick practice
A sealed, rigid container of gas is warmed. Predict the pressure change and explain it using particles.
Need a hint?
The amount of gas and container volume stay constant. What changes about collisions?
Check your reasoning after trying
Pressure increases. Particles move faster, so they collide with the walls more often and with greater force.
For more written practice, use Lesson 4 in your worksheet. Your teacher will discuss those answers in class.
Try it: States of Matter
Use the Phase Changes tab. Add heat and observe the particles and pressure reading while keeping the amount of gas and container volume fixed.
Open simulation in a new tab ↗