+- The Lumin Archive (https://theluminarchive.co.uk)
+-- Forum: The Lumin Archive — Core Forums (https://theluminarchive.co.uk/forumdisplay.php?fid=3)
+--- Forum: Equations Archive (https://theluminarchive.co.uk/forumdisplay.php?fid=83)
+--- Thread: The Ideal Gas Law — Why Gases Expand (/showthread.php?tid=429)
The Ideal Gas Law — Why Gases Expand - Leejohnston - 01-08-2026
## The Ideal Gas Law — Why Gases Expand
### 1. The Equation
PV = nRT
---
### 2. What Each Symbol Means
- P = pressure
- V = volume
- n = number of moles
- R = gas constant
- T = temperature (kelvin)
---
### 3. What the Equation Is Telling Us
Pressure, volume, and temperature are linked.
Changing one forces the others to respond.
---
### 4. Where It Comes From (Intuition)
Gas particles are in constant motion.
Heating them increases motion → more collisions → higher pressure.
---
### 5. Worked Example
If temperature increases while volume stays fixed:
- pressure must rise
This is why sealed containers can burst when heated.
---
### 6. Real-World Applications
- Weather balloons
- Engines
- Refrigeration
- Atmospheric science
---
### 7. Common Misconceptions
- Gases expand because they “want to” → false
- Temperature is heat → false
- Pressure and force are the same → false
---
### Try It Yourself
Why do hot air balloons rise?