The decomposition of ozone may occur through the two-step mechanism shown below:
step 1 O3 ----> O2 + O
step 2 O3 + O ---> 2O2
The oxygen atom is considered to be: a catalyst or reaction intermediate?
How am I supposed to be able to tell the difference between the two? I know a catalyst speeds up a reaction without be consumed, but I'm not sure on how to be able to identify a reaction intermediate.
A reaction intermediate is a short-lived, high-energy molecule formed during a chemical reaction. It is not present in the initial reactants or final products, but rather forms and reacts in the middle of the reaction pathway.
In the given reaction:
step 1 O3 ----> O2 + O
step 2 O3 + O ---> 2O2
The oxygen atom (O) is a reaction intermediate because it is formed in step 1 and then consumed in step 2. It is not present in the initial reactant (O3) or the final product (O2). So, the oxygen atom is a reaction intermediate.
A catalyst, on the other hand, would be a substance that participates in the reaction but is not consumed in the overall reaction. A catalyst would be present in both the reactants and the products of the reaction. In this case, there is no substance that fulfills this criterion, so there is no catalyst in this reaction.
To determine whether the oxygen atom is considered a catalyst or a reaction intermediate in this specific reaction mechanism, let's first define what each term means:
1. Catalyst: A catalyst is a substance that speeds up a chemical reaction by providing an alternative reaction pathway with lower activation energy, without being consumed in the reaction. Essentially, it increases the rate of reaction but remains unchanged by the end.
2. Reaction Intermediate: A reaction intermediate is a species that forms during the reaction but is consumed in a subsequent step, ultimately leading to the production of the desired products. It is an intermediate species between the reactants and the final products.
Now, let's analyze the two-step mechanism you provided:
Step 1: O3 → O2 + O
In this step, ozone (O3) decomposes into oxygen gas (O2) and an oxygen atom (O). Here, the oxygen atom is not formed in the first step and doesn't appear in the final products; it's consumed in a subsequent step.
Step 2: O3 + O → 2O2
In this step, the oxygen atom (O) that was generated in the first step reacts with another ozone molecule (O3) to form two molecules of oxygen gas (O2). Here, the oxygen atom is consumed, participating in the reaction to produce the final products, but it is not regenerated or independent of the subsequent step.
Based on this analysis, the oxygen atom is considered a reaction intermediate in this mechanism. It is formed in Step 1 and consumed in Step 2, making it an intermediate species between the reactants and the final products.
To determine whether the oxygen atom in the given reaction is a catalyst or a reaction intermediate, we need to understand their definitions and characteristics.
A catalyst is a substance that increases the rate of a chemical reaction by providing an alternative reaction pathway with a lower activation energy. It is not consumed in the reaction and is regenerated at the end. In other words, a catalyst speeds up the reaction without being consumed or permanently changed.
On the other hand, a reaction intermediate is a species that is formed and consumed during the course of a reaction but is not present in the overall balanced equation. Reaction intermediates are typically formed in the reaction mechanism and act as transient species that help convert reactants into products.
In the given mechanism, we see that the oxygen atom is initially formed in step 1 and released as a product (O) without being regenerated or participating in subsequent steps. This indicates that the oxygen atom is not a catalyst since it is consumed in step 1. Therefore, in this mechanism, the oxygen atom is considered a reaction intermediate.
To summarize:
- A catalyst is not consumed during the reaction and speeds up the reaction.
- A reaction intermediate is a species formed and consumed during the reaction, assisting in the conversion of reactants to products.