Question

The central idea of the collision model is that molecules must collide in order to react. Give two reasons why not all collisions of reactant molecules result in product formation.

Short answer

The two reasons why not all collisions of reactant molecules result in product formation are:

(a) Energy of activation.

(b) Favorable orientation.

Step-by-step solution

Understanding how the energy of activation works for a reaction to take place.

The activation energy of a chemical reaction is closely related to its rate. Specifically, higher the activation energy, the slower the chemical reaction will be. This is because molecules can only carry out the reaction only when they have reached the peak of the activation energy barrier.

In context to the given question, the collision of the reactant molecules always does not leads to formation of product, because these collisions should have enough energy to produce the reaction by having an equal or much larger collision energy than the activation energy.

Understanding how orientation works for a reaction to take place.

The relative orientation of the reactants leads to establishment of new bonds which are essential for product formation.Only if the reactants are in a favorable orientation in the moment of collusion, so the product can be formed.