How would adding the catalyst nitrogen monoxide (NO) affect this reaction? 2SO2 (g) + O2 (g) → 2SO3 (g)

NO decreases the activation energy and increases the rate of a reaction

Explanation:

To fully comprehend this problem, we wish to understand the role of a catalyst in a chemical reaction. Catalyst is a substance which is essentially consumed and then reproduced (that said, its mass remains the same and the net mass consumed is equal to 0) in a chemical reaction which:

decreases the activation energy barrier - that is, the minimum amount of energy required for a successful collision between molecules leading to a chemical reaction; increases the rate of a reaction: the reaction proceeds faster. This is achieved based on the fact that the activation energy is decreased.

Addition of a nitrogen monoxide catalyst would therefore decrease the activation energy and increase the rate of a reaction.

Now, in terms of equilibrium (if the reaction is at equilibrium, as just a right arrow is indicated), since nitrogen monoxide is a gas, there would be no shift in equilibrium towards the products or reactants, as addition of an inert gas to an equilibrium system would decrease the partial pressures of each component equally.