Question

Why does a catalyst increase the rate of a reaction?What is the difference between a homogeneous and aheterogeneous catalyst? Would a given reaction necessarily

have the same rate law for both a catalyzed andan uncatalyzed pathway? Explain.

Short answer

The catalyst increases the rate of reaction. The catalyst has the property of reaction intermediate formation. This intermediate further reacts/changes to form the product.

They reduce the activation energy of reactants and products to fasten rate the reaction rate. Lowering the reaction potential indicates the production of a better product.

Step-by-step solution

Difference between the homogeneous and heterogeneous catalyst

Homogeneous catalyst:This is defined as the catalyst in a particular reaction. The phase of the substrate and catalyst must be the same and the reacting system is homogeneous.

For example, the formation of SO₃ compound from SO₂ and O₂ takes place. In the process, NO is used as a homogenous catalyst.

$S{O}_2+O_2\stackrel{NO\left(g\right)}{\leftrightarrows }S{O}_3$

Heterogeneous catalyst:This is defined as the catalyst in a particular reaction the phase of the substrate and catalyst must be different and the reacting system is heterogeneous.

For example, ethylene and H₂react to form ethane in presence of Pt/Ni/Pd, which are solids and the reactants are in the gaseous phase.

Describing a given reaction necessarily means having the same rate law for both a catalyzed and an uncatalyzed pathway.

The catalysts decrease the activation energy. It changes the mechanism of the reaction by altering it.

For any given reaction, the rate law depends upon the catalyst. During the reaction, they act as an intermediate to speed up the reaction. This reaction intermediate helps to get a better product.

The uncatalyzed reaction will have a one-step mechanism, while the catalyzed reaction will have a two-step mechanism. The two-step mechanism with less activation potential is preferable.