* Sulfur dioxide (SO2) dissolves in water. Sulfur burning in air produces sulfur dioxide gas. This gas is soluble in water, and it reacts with the water molecules to form sulfurous acid (H2SO3).
* The solution becomes acidic. Sulfurous acid is a weak acid. This means the solution will have a lower pH than pure water, indicating acidity.
* The solution will have a characteristic pungent odor. Sulfurous acid has a pungent, suffocating odor, which is often described as similar to burning matches.
Chemical Reaction:
The reaction that occurs is:
SO2(g) + H2O(l) ⇌ H2SO3(aq)
This reaction is reversible, meaning that the sulfurous acid can decompose back into sulfur dioxide and water.
Note: This reaction is also responsible for the formation of acid rain. When sulfur dioxide is released into the atmosphere, it can dissolve in rainwater and form sulfuric acid, which can then fall to the ground as acid rain.
