Question

For each of the following pairs of reaction diagrams, identify which of the pairs iscatalyzed:

Short answer

(a) Reaction diagram (b) is a catalyzed reaction.

(b) Reaction diagram (b) is a catalyzed reaction.

Step-by-step solution

Definition of Catalyst

Catalysts are substances which increase the rate of the reaction without getting used up by themselves while decreasing the activation energy of the reaction.

• A catalyst increases the rate of reaction.
• Catalyst accelerates the rate of a reaction by decreasing the activation energy.
• Catalysts may provide different reaction mechanisms involving extra steps in the reaction and lower the activation energy, simultaneously increasing the reaction rate.
• Catalyst is regenerated during the reaction.

(a) Reaction diagram (b) uses a catalyst

1. The two reaction diagrams depict the same reaction, one with a catalyst and another without a catalyst.
2. The two reaction diagrams depict a two-step reaction mechanism involving two transition states.
3. We can also notice an intermediate species between the two transition states.
4. But a small change is observed in the second transition state, which is lower in diagram (b) than in diagram (a). This indicates the presence of a catalyst in diagram (b).

(b) Reaction diagram (b) uses a catalyst 

1. The two reaction diagrams depict the same reaction, one with a catalyst and another without a catalyst.
2. The two reaction diagrams depict two-step reaction mechanisms involving two transition states.
3. But a small change is observed in the first transition state, which is lower in diagram (b) than in diagram (a). This indicates the presence of a catalyst in diagram (b).

Thus, the reaction diagram (b) is catalyzed among both pairs of the reaction diagrams (a) and (b).