A chemical reaction involves the conversion of reactant molecules to product molecules with cleavage and formation of some chemical bonds. This conversion requires some amount of energy which comes from the collision of reactant molecules. It means reactant molecules must have some energy that induces collision between them and results the formation of product molecules. Sometimes reactant molecules do not have enough kinetic energy to collide with each other. Hence the reaction will not furnish and requires some energy that can provide in terms of heat.
Some of the reactions require large amount of energy that cannot be provided by external sources. In such cases, we can use catalyst which is a substance that reduces the activation energy for the reaction and quickly form the product. Do you know what activation energy is? Activation energy is the minimum amount of energy requires for effective collision between reactant molecules.
The presence of catalyst reduces the activation energy by bonding with reactant molecules. It regenerates in the chemical reactions at the end of reaction. Hence we can say that catalyst does not take part in the reaction and not changed by the reaction. They can be a transition metal or transition metal oxide or an enzyme. Catalyst provides a convenient surface which enables a different route for a chemical reaction with low activation energy.
The surface of catalyst makes the reacting particles more active results more of the collisions that lower the activation energy. In a chemical reaction, there are cleavage and rearrangement of chemical bonds which results the formation of transition state. Transition state is a high energy structure with incomplete chemical bonds. Due to high energy, it readily decomposes to product. The energy difference between reactant and transition state is called the Energy of Activation, or Ea. Catalyst w provides an alternate route with low activation energy. Remember catalysts cannot affect the chemical equilibrium shift and equilibrium constant.
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