Molecular Speeds

The Maxwell–Boltzmann distribution

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Molecular speeds follow the Maxwell–Boltzmann distribution; they scale as $\sqrt{T/m}$.
• At equal temperature, lighter molecules move faster.
• The fast tail lets light gases escape from planets.

Steps

1. A spread of speeds
2. Helium versus nitrogen
3. How fast is air?
4. Same speeds, different gases
5. Hydrogen versus oxygen
6. Losing hydrogen