Lecture 2 – Factors affecting Rate of Reactions

Factors affecting Rate of Reactions

The rate of reaction is affected by the 5 following factors:

i.                    Temperature

ii.                  Concentration

iii.                Particle size of the reactants

iv.               Pressure

v.                 Presence of a catalyst

Temperature:

Temperature directly affects the rate of a reaction; the higher the temperature, the faster the rate of the reaction is and vice versa.

Effect of heat on Endothermic reactions:

Heat or high temperatures increase the K.E of the reacting particles and faster moving and frequently colliding particles form products, quickly.

Effect of heat on Exothermic reactions:

Heat adversely affects the rate of exothermic reactions and the rate of the temperature decreases at high temperatures and vice versa, for exothermic reactions.

Examples:

i.                    Milk sours more in summers than in winters.

ii.                  Food goes bad more in summers than in winters.

iii.                Sugar dissolves more easily in warm/hot water than cold water.

Pressure:

Pressure directly affects the rate of gaseous reactions. The higher the pressure, the faster the rate of the reaction, and vice versa. Higher pressure means that the reacting particles collide more often and more collisions mean that more products are formed per unit time.

Concentration of reactants:

Concentration of reactants directly affects the rate of reactions. More the reacting particles, more are the collisions between the particles and quicker the formation of products.