Do catalysts get consumed in a chemical reaction?

Do catalysts get consumed in a chemical reaction?

• A. They are consumed in the reaction.
• B. They are not consumed in the overall reaction but may participate in the mechanism.
• C. They do not affect the rate.
• D. They permanently shift the equilibrium.

Answer: (B)

The main idea here is that a catalyst provides a different, lower-energy route for the reaction to occur, so more molecules can react in a given time. It does this by offering an alternative mechanism that reduces the activation energy required for the process. Importantly, the catalyst itself is not consumed in the overall reaction; after the reaction runs its course, the catalyst is present in essentially the same amount as at the start. It may participate in the mechanism by forming temporary intermediates or binding with reactants during steps, but it is regenerated by the end of the process. That means the net amount of catalyst remains unchanged, so the overall stoichiometry doesn’t include a consumed catalyst. Because both forward and reverse steps are accelerated by the catalyst, the rate at which equilibrium is reached increases, but the equilibrium position—the ratio of products to reactants at a given temperature—stays the same. A statement suggesting the catalyst is consumed or that it permanently shifts the equilibrium doesn’t fit how catalysts operate.

The main idea here is that a catalyst provides a different, lower-energy route for the reaction to occur, so more molecules can react in a given time. It does this by offering an alternative mechanism that reduces the activation energy required for the process. Importantly, the catalyst itself is not consumed in the overall reaction; after the reaction runs its course, the catalyst is present in essentially the same amount as at the start.

It may participate in the mechanism by forming temporary intermediates or binding with reactants during steps, but it is regenerated by the end of the process. That means the net amount of catalyst remains unchanged, so the overall stoichiometry doesn’t include a consumed catalyst. Because both forward and reverse steps are accelerated by the catalyst, the rate at which equilibrium is reached increases, but the equilibrium position—the ratio of products to reactants at a given temperature—stays the same. A statement suggesting the catalyst is consumed or that it permanently shifts the equilibrium doesn’t fit how catalysts operate.