On the catalyst surface, reactant molecules rearrange and form products more easily. Which statement best describes this step?

On the catalyst surface, reactant molecules rearrange and form products more easily. Which statement best describes this step?

• A. Reactants rearrange and form products more easily
• B. Reactants are adsorbed but do not react
• C. The surface becomes poisoned
• D. The products are immediately desorbed without reaction

Answer: (A)

In heterogeneous catalysis, the critical stage on the catalyst surface is the surface reaction, where adsorbed reactants rearrange and form products that can then leave the surface. The catalyst provides a site where bonds can be broken and formed more easily, lowering the energy barrier for the reaction compared to the gas phase. This makes the rearrangement and bond-making steps on the surface faster than if the molecules stayed unreacted or desorbed without reacting. So the statement that reactants rearrange and form products more easily on the surface best describes this surface reaction step. If it were only adsorption with no chemical change, there would be no product formation; if the surface became poisoned, active sites would be blocked and the reaction would slow; and if desorption occurred immediately without any reaction, no products would be produced.

In heterogeneous catalysis, the critical stage on the catalyst surface is the surface reaction, where adsorbed reactants rearrange and form products that can then leave the surface. The catalyst provides a site where bonds can be broken and formed more easily, lowering the energy barrier for the reaction compared to the gas phase. This makes the rearrangement and bond-making steps on the surface faster than if the molecules stayed unreacted or desorbed without reacting.

So the statement that reactants rearrange and form products more easily on the surface best describes this surface reaction step. If it were only adsorption with no chemical change, there would be no product formation; if the surface became poisoned, active sites would be blocked and the reaction would slow; and if desorption occurred immediately without any reaction, no products would be produced.