Sulfur dioxide is oxidized to sulfur trioxide in the following sequence of reactions: 2 SO2(g) + 2 NO2(g) → 2 SO3(g) + 2 NO(g) 2 NO(g) + O2(g) → 2 NO2(g). (b) Identify any molecule that acts as a catalyst or intermediate in this reaction.

Verified step by step guidance

1. Step 1: Understand the role of a catalyst and an intermediate in a chemical reaction. A catalyst is a substance that increases the rate of a reaction without being consumed in the process. An intermediate is a species that is formed in one step of a reaction mechanism and consumed in another.
2. Step 2: Analyze the given reactions to identify any species that appear in both reactions. Look for molecules that are produced in one reaction and consumed in another, as these are potential intermediates.
3. Step 3: Examine the first reaction: 2 SO2(g) + 2 NO2(g) → 2 SO3(g) + 2 NO(g). Notice that NO is produced in this reaction.
4. Step 4: Examine the second reaction: 2 NO(g) + O2(g) → 2 NO2(g). Notice that NO is consumed in this reaction, and NO2 is regenerated.
5. Step 5: Conclude that NO is an intermediate because it is produced in the first reaction and consumed in the second, while NO2 acts as a catalyst because it is consumed in the first reaction and regenerated in the second.