Factors Affecting Rate of Reaction

At the end of the article, you will able to describe Factors Affecting Rate of Reaction. Let’s first discuss what exactly the rate of reaction is and it occurs.

Rate of Reaction

The rate of reaction is the rate at which chemical reaction proceeds. In simpler terms, The rate of reaction is how fast or how slow a chemical reaction occurs.

How does a chemical reaction occur?

Answer– Reactions occur when two or more molecules collide with each other and must possess enough activation energy which is the minimum amount of energy needed to start a reaction chemical reactions.

Factors Affecting Rate of Reaction

There are numerous factors affecting the rate of reaction are explained below. The rates of chemical reactions are influenced by a number of factors. These are :

  • Concentration of reactants
  • Temperature
  • Presence of Catalyst
  • Nature of Reactants
  • Surface area
  • Exposure to Radiation


Increase in concentration the of reactants always gives more yield of the products irrespective of the nature of the reaction and the conditions which govern the reaction.

If the concentration of a dissolved reactant is increased, the reactant particles become more crowded. Therefore there is a greater chance of the particles colliding. Thus, the rate of reaction increases.Factors Affecting Rate of Reaction

We can now conclude the relationship between the concentration of reactant and the rate of reaction is directly proportional.

Concentration ∝ Rate of Reaction

  • Higher the concentration, faster the rate of reaction and
  • Lower the concentration, the slower the rate of reaction

Must Read- Illustration of Experiment.


Most of the chemical reactions which are slow at lower temperature become fast upon heating. In fact, temperature provides heat energy to the reactant species. They move and collide at the faster rate and give more products.

Once a substance is heated, the particles move more quickly and they have more kinetic energy. As a result, the particles collide more often.

More of the collisions = Successful rate of reaction.Factors Affecting Rate of Reaction

Therefore, increases the same with the concentration, the temperature is also directly proportional to the rate of reaction.

Temperature ∝ Rate of Reaction

Temperature ∝ Concentration ∝ Rate of Reaction


This plays a crucial role in Factors Affecting Rate of Reaction. The effect of the catalyst on the reaction rate is very significant. A number of catalysts are used in chemical reactions of industrial importance.


  • Catalysts (enzymes) lowered the activation energy and increase the frequency of collisions.
  • Catalyst does not participate in the reaction.

Enzymes lowered the activation energy of a chemical reaction and increase the rate of the reaction without being consumed in the process. Catalyst works by increasing the frequency of collisions between reactants altering the orientation of reactants so that more collisions are effective reducing intermolecular bonding within reactant molecules or donating electron density to the reactants. Therefore, we can say that

  • The lower the activation energy the faster the rate of reaction.
  • A higher activation energy the slower the rate of reaction.

Nature of Reactants

Chemical reactions involving different reactants do not proceed at the same speed. For example, combustion of nitric oxide (NO) is faster as compared to that of carbon monoxide (CO).

Surface Area

Smaller reactant particles provide a greater surface area which increases the chance for particle collisions. So, the reaction rates increase. Therefore,

  • Larger particles have small surface area 
  • While small particles of greater surface area

If the surface area of a reactant is increased by cutting the substance into small pieces by grinding it into a powder. More particles are exposed to the other reactant increasing the rate of reaction.

In the laboratory, we quite often prefer granulated zinc in preference of lump of the metal while preparing hydrogen gas on reacting with the dilute hydrochloric acid or dilute sulphuric acid. Actually, granulated zinc has the Greater surface area available for the attack by the acid than the lump of zinc. Therefore, it reacts at a faster rate.


Many chemical reactions known as photochemical reactions are carried in the presence of sunlight. For example,

H2(g) + Cl2(g) → 2HCl(g)

In these types of reactions, the photons of light are the source of energy which helps in breaking the bonds in the reacting molecules so that may react and form products.

This is all about the Factors Affecting Rate of Reaction.

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