Question

In some cases it is found that a large number of colliding molecules have energy more than the threshold value, yet the reaction is slow, why?

Answer 1

1. In some cases, even though a large number of colliding molecules have energy more than the threshold value, the reaction is slow because proper orientation of molecules during collision is also essential for a successful reaction.
2. If the molecules collide with incorrect orientation, effective collisions do not occur, and hence the reaction rate remains slow. Therefore, for a fast reaction, both sufficient energy and correct orientation are necessary.