To determine how adding the catalyst nitrogen monoxide (NO) would affect the reaction given by:
[tex]\[ 2 \text{SO}_2 (g) + \text{O}_2 (g) \rightarrow 2 \text{SO}_3 (g) \][/tex]
Let's carefully analyze the effect of catalysts on chemical reactions.
### Definition and Role of Catalysts
A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It works by providing an alternative reaction pathway with lower activation energy, enabling more reactant molecules to have enough energy to react upon collision.
### Options Analysis
- Option A: NO increases the rate at which SO₃ molecules are formed.
- A proper function of a catalyst is to increase the rate of the reaction. Therefore, adding NO should increase the rate at which SO₃ is formed since it will provide a lower activation energy pathway for the reaction.
- Option B: NO reacts with SO₃ to produce more SO₂ molecules.
- NO acting as a catalyst should not be consumed in the reaction or produce additional products other than those in the original reaction equation.
- Option C: NO decreases collisions between the SO₂ and O₂ molecules.
- The role of a catalyst is to increase the rate of reaction, not decrease the collisions between reactant molecules. This would contradict the purpose of using a catalyst.
- Option D: NO increases the concentration of the SO₂ and O₂ molecules.
- A catalyst does not change the concentrations of the reactants; it only changes the rate at which products are formed by lowering the activation energy.
- Option E: NO increases the activation energy of the SO₂ and O₂ molecules.
- Increasing the activation energy would actually slow down the reaction, which is the opposite of a catalyst's role.
### Conclusion
The correct answer is: NO increases the rate at which SO₃ molecules are formed.
Therefore, the proper answer is:
- A. NO increases the rate at which SO₃ molecules are formed.
