Sulfur dioxide (SO₂) and sulfur trioxide (SO₃) are both gasses that can be involved in the formation of sulfuric acid (H₂SO₄) through different synthesis processes. However, when considering the dissolution of sulfur trioxide in water to produce sulfuric acid, it is crucial to note that this reaction is highly exothermic and can lead to violent reactions.
When SO₃ is dissolved in water, it does not simply mix; instead, it reacts to form sulfuric acid through the reaction:
\[ \text{SO}_3(g) + \text{H}_2\text{O}(l) \rightarrow \text{H}_2\text{SO}_4(aq) \]
This reaction generates a significant amount of heat, which can cause rapid boiling and splattering of concentrated sulfuric acid, posing safety risks. Additionally, because sulfur trioxide is a gas at room temperature, managing its dissolution in water safely becomes challenging.
For these reasons, it is generally safer and more controlled to prepare sulfuric acid through indirect means, such as first producing sulfur dioxide, converting it to sulfur trioxide, and then handling the final acid production under controlled conditions.