Activation energy1. According to the kinetic theory of matter, particles of matter are in continuous motion and

constantly in collision with each other.2. During a reaction, the particles of the reactants, whether atoms, molecules or ions, must

collide with each other for bond breaking and then bond formation to occurs.3. Only those collisions which achieved a minimum amount of energy, called activation energy, and with the correct orientation, will result in a reactions.4. These collisions are known as called effective collisions.5. If the particles collide with energy less than the activation energy needed for reaction or with the wrong orientation, they simply bounce apart without reacting.6. These collisions are known as ineffective collisions.7. In the energy profile diagram, the activation energy is the difference is energy between the energy of the reactants and the energy shown by the peak of the curve,8. It is the energy barrier that must be overcome by the colliding particles of the reactants in order for reaction to occur.9. The number of effective collisions occurring in one second is called the frequency of effective collision.10. when the frequency of effective collision is high, the rate of reaction is high.

Use of collision theory to explain the effect of the size of reactant /

total surface area on the rate of reaction

• When the size of a fixed mass of solid reactant is smaller, the total surface area exposed to

collision with the particles of the other reactants is bigger.

• Thus, the frequency of collision among the reacting particles at the surface of the solid

reactant increases.• This leads to an increase in the frequency of

effective collision and hence, a higher rate of reaction.

Use of collision theory to explain the effect of concentration on the rate of reaction

1.When the concentration of the solution of a reactant increase, the number of particles per

unit volume of the solution of this reactant also increase.

2. with more particles per unit volume of the solution, the number of collisions per unit time

between the reacting particles increases.3. Thus, the frequency of effective collision

increases and hence, the rate of reaction increases

Use of collision theory to explain the effect of Temperature on the rate of reaction

1. When the temperature increase, the average kinetic energy of the reacting particles increases.

2. The particles move faster and collide more often with one another. The frequency of collision among the reacting particles increases.

3. Particles also have more energy to overcome the activation energy.

4. These changes increase the frequency of effective collision.

5. Hence, the rate of reaction increase.

Use of collision theory to explain the effect of Pressure on the rate of reaction

1. when the pressure of gaseous reactant increases, the particles are compressed to occupy a smaller volume. The number of gas particles per unit volume increases.

2. The frequency of collision among the reacting particles increases.

3. This increases the frequency of effective collision.

4. Hence, the rate of reaction increases.

Use of collision theory to explain the effect of catalyst on the rate of reaction

1. When a positive catalyst is used in a chemical reaction, it provides as alternative path with a lower activation energy.

2. More colliding particles are able to overcome the lower activation energy.

3. The increases the frequency of effective collision.

4. Hence the rate of reaction increases.

Catalyst in Industry

Size of reactant Concentration Temperature CatalystSize of reactant

__________, total surface area

_______________

At higher concentration, number of particles

____________

Temperature ________, kinetic energy of reactant

____________

Catalyst will provide ___________ path with

lower ___________________

_______________

Thus

Particles will collide __________________

cause

Frequency of collision _________________

Frequency of effective collision _________________

Hence

The rate of reaction_________________