collision theory and arreneius equation difference???

It is pretty obvious that if you have a situation involving two species they can only react together if they come into contact with each other. They first have to collide, and then they may react.

Why "may react"? It isnt enough for the two species to collide - they have to collide the right way around, and they have to collide with enough energy for bonds to break.

(The chances of all this happening if your reaction needed a collision involving more than 2 particles are remote. All three (or more) particles would have to arrive at exactly the same point in space at the same time, with everything lined up exactly right, and having enough energy to react. Thats not likely to happen very often!)

The orientation of collision

Consider a simple reaction involving a collision between two molecules - ethene, CH₂=CH₂, and hydrogen chloride, HCl, for example. These react to give chloroethane.

As a result of the collision between the two molecules, the double bond between the two carbons is converted into a single bond. A hydrogen atom gets attached to one of the carbons and a chlorine atom to the other.