Collision frequency refers to how often molecules collide with each other in a given time period. For example, in gases, molecules are in constant motion and crash into each other regularly.
The collision frequency is influenced by factors like:
- Molecular size: Smaller molecules tend to collide more frequently.
- Temperature: Higher temperatures increase the speed of molecules, leading to more collisions.
- Number density: More molecules in a given volume lead to a higher collision frequency.
In the case of hydrogen \(\text{H}_2\), it has a small molecular size which means it collides more frequently with other hydrogen molecules. However, due to its small size and the way mean free path works, it travels a longer distance on average before each collision.
Understanding collision frequency helps us grasp why hydrogen travels further, making its mean free path the longest among the listed gases.