Answer:
The answer is a catalyst, specifically vanadium(V) oxide, V2O5.
Step-by-step explanation:
A catalyst is needed for the reaction SO2-SO3. A catalyst is a substance that speeds up a chemical reaction without being consumed by the reaction. The most common catalyst used for the SO2-SO3 reaction is vanadium(V) oxide, V2O5.
The reaction SO2-SO3 is a reversible reaction. This means that the products of the reaction can react back to form the reactants. The catalyst helps to shift the equilibrium of the reaction towards the products.
The reaction SO2-SO3 is an important industrial reaction. It is used to produce sulfuric acid, which is a major industrial chemical.