Chemistry – Chemical reactions - Rate of reaction | e-Consult

Heating the reaction mixture increases the rate of reaction between H₂O₂ and MnO₂ due to the following reasons, explained through collision theory:

Diagram:

The diagram illustrates the relationship between kinetic energy and the number of successful collisions. The key points are:

• (a) Number of particles per unit volume (Concentration): Heating the mixture does not directly change the concentration of H₂O₂ or MnO₂. Therefore, the number of collisions per unit time remains relatively constant.
• (b) Frequency of collisions between particles: Heating increases the speed of the reactant particles, leading to a higher frequency of collisions. More collisions mean a greater opportunity for successful reactions.
• (c) Kinetic energy of particles: Heating increases the average kinetic energy of the particles. This is the most important factor. A greater proportion of the collisions will now have kinetic energy equal to or greater than the activation energy (E_a). This significantly increases the number of successful collisions.
• (d) Activation energy (E_a): The activation energy remains constant. However, the increased kinetic energy at higher temperatures means that a larger fraction of the reactant particles possess the energy required to overcome this barrier. This results in a much higher rate of reaction.

In summary, heating provides the reactant particles with more kinetic energy, increasing the frequency of collisions with sufficient energy to overcome the activation energy barrier. This leads to a significantly faster rate of reaction.