STUDENT SPACE · TOPIC 5
Diffusion and chapter review
Explain diffusion-rate differences and apply the particle model across the chapter.
The essentials
- Diffusion happens because particles move randomly; the net movement is down a concentration gradient.
- Higher temperature increases particle speed and usually increases the rate of diffusion.
- At the same temperature, lighter gas molecules diffuse faster than heavier gas molecules.
Key vocabulary
| English | Chinese |
|---|---|
| relative molecular mass | 相对分子质量 |
| ammonia | 氨 |
| hydrogen chloride | 氯化氢 |
| ammonium chloride | 氯化铵 |
| net movement | 净移动 |
| evidence | 证据 |
Quick practice
Two gases at the same temperature have relative molecular masses of 17 and 36.5. Which is expected to diffuse faster?
Need a hint?
Compare molecular mass while keeping temperature the same.
Check your reasoning after trying
The gas with relative molecular mass 17 diffuses faster because its molecules have a higher average speed at the same temperature.
For more written practice, use Lesson 5 in your worksheet. Your teacher will discuss those answers in class.
Try it: States of Matter
Compare particle motion before and after heating the same substance. The simulation illustrates motion; it does not directly measure diffusion rates.
Open simulation in a new tab ↗