Rate of reaction is defined as the change in quantity of reactants or products per unit time. The average rate is calculated over an interval of time, while the instantaneous rate is the actual rate at a given time. Several factors affect the rate of reaction, including the total surface area and concentration of reactants, temperature, use of catalysts, and pressure for gaseous reactants. According to collision theory, the rate of reaction depends on the frequency and effectiveness of collisions between reactant particles, which must achieve the minimum activation energy and correct orientation.

2. Rate of reaction
 Rate of reaction is the measurement of
the speed which reactants are converted into
products in a chemical reaction / change in a
selected quantity during a reaction per unit
time.
 Average rate of reaction is the average value of
the rate of reaction over an interval of time.
 Instantaneous rate of reaction / Rate of
reaction at a given time are the actual rate of
reaction at that instant.

4.  Total surface area of solid reactant
 Concentration of reactant
 Temperature of reactant
 Use of catalyst
 Pressure of gaseous reactant

7.  Take note :

8.  The smaller the size (increase the total surface
area), cm3, of the solid reactant, the higher the rate
of reaction, cm3 s-1 or cm3 min-1.
 Explanation:

9. Effect of concentration of a liquid
reactant on the rate of reaction
The higher the concentration, mol dm-3, of a
liquid reactant, the higher the rate of
reaction, mol dm-3 s-1 or mol dm-3 min-1.

12.  Increase in temperature, the higher the rate
of reaction.

13.  Alters the rate of reaction
 It is specific in its action. It can only catalyse a
particular reaction
 Does not change the quantity of products formed
 Only small amount of catalyst is needed to increases
the rate of reaction. (An increase in the quantity of
catalyst will increase the rate of reaction but only a
very slight increase.)
 Catalyst remains chemically unchanged but may
undergo physical changes.

16. (catalyst)

18. catalyst

19. Effect of pressure on the rate of
reaction
• Increase in pressure, the higher the rate of
reaction (reversible reaction and gaseous
reactants and gaseous product).

21. 1.3 Collision Theory
• According to kinetic theory of matter : Particles of matter are
in continuous motion & constantly in collision with each other.
• Collision theory states a reaction occur when the particle of
the reactant collide with each other with
the correct orientation and achieve activation energy.
• Collision theory also states that the rate of reaction can be
determined by frequency of collision / number of collisions
per second & magnitude of Ea.
• Collision which achieve a minimum amount of activation
energy & with correct orientation will result in reaction.
(Effective collision)
• Ineffective collision is the particles that collide with
energy less than activation energy or wrong orientation.

22. Activation energy, Ea
• The energy barrier that must be overcome by
the colliding particles of the reactants so that
the reaction can occur.
• Can be visualized by sketching the energy
profile diagrams.