The presence of a heterogeneous catalyst significantly affects the rate of a chemical reaction by providing an alternative reaction pathway with a lower activation energy. Heterogeneous catalysts are typically solid materials with a different phase than the reactants, which are usually in gas or liquid form. The catalyst remains unchanged after the reaction and can be reused.The surface chemistry and mechanisms involved in the heterogeneous catalysis process can be explained through the following steps:1. Adsorption: The reactant molecules also called adsorbates are adsorbed onto the surface of the catalyst also called the adsorbent . This process involves the formation of chemical or physical bonds between the reactant molecules and the catalyst's surface. The adsorption step is crucial as it brings the reactants closer together, facilitating their interaction.2. Activation: The adsorbed reactant molecules are activated by the catalyst, which weakens their chemical bonds and lowers the activation energy required for the reaction to occur. The catalyst's surface may also undergo temporary structural changes to accommodate the reactants, further facilitating the reaction.3. Reaction: The activated reactant molecules interact with each other on the catalyst's surface, forming the desired product molecules. This step is the actual chemical transformation that occurs due to the lowered activation energy provided by the catalyst.4. Desorption: The product molecules are released from the catalyst's surface, making room for new reactant molecules to be adsorbed and continue the catalytic cycle. The desorption process is essential for maintaining the catalyst's activity and preventing its surface from becoming saturated with product molecules.5. Regeneration: The catalyst's surface returns to its original state, ready to participate in subsequent catalytic cycles. In some cases, the catalyst may require periodic regeneration to remove any accumulated impurities or byproducts that could hinder its performance.Overall, the presence of a heterogeneous catalyst enhances the rate of a chemical reaction by providing an alternative reaction pathway with a lower activation energy. The catalyst's surface plays a crucial role in adsorbing, activating, and facilitating the interaction between reactant molecules, ultimately leading to the formation of the desired products.