give reason why all collisions between reactant molecules do not lead to a reaction

Not all collisions between reactant molecules lead to a reaction due to the following reasons:

1. Orientation of Molecules: For a reaction to occur, the molecules must collide in a specific orientation that allows the breaking and forming of bonds. If the molecules collide in an incorrect orientation, no reaction will occur.

2. Energy Threshold: There is a minimum amount of energy required for a reaction to occur, known as the activation energy. If the colliding molecules do not have this minimum energy, they will simply bounce off each other and no reaction will occur.

3. Physical and Chemical Conditions: The physical and chemical conditions under which the collision occurs, such as temperature, pressure, and the presence of a catalyst, can also affect whether a reaction occurs. For example, if the temperature is too low, the molecules may not have enough kinetic energy to overcome the activation energy barrier.

4. Stability of Reactants: Some molecules are more stable than others and therefore less likely to react. The stability of a molecule can be influenced by factors such as its structure and the nature of the bonds between its atoms.

5. Presence of Inhibitors: In some cases, a substance known as an inhibitor can prevent a reaction from occurring by either temporarily or permanently binding with one of the reactants, thus preventing it from colliding with other molecules.