SO₂ + H₂O ⇌ H₂SO₃
Here's what happens:
* Sulfur dioxide dissolves in water: SO₂ is a gas that dissolves in water.
* Formation of sulfurous acid: When SO₂ dissolves, it reacts with water molecules to form sulfurous acid.
* Equilibrium: The reaction is reversible, meaning it can proceed in both directions. Some of the sulfurous acid can decompose back into sulfur dioxide and water.
Sulfurous acid is a weak acid, meaning it doesn't completely ionize in water. However, it can contribute to the acidity of solutions, which is important in processes like:
* Acid rain: Sulfur dioxide released from burning fossil fuels dissolves in rainwater to form sulfurous acid, which contributes to acid rain.
* Industrial processes: Sulfurous acid is used in some industrial processes, like the production of paper and textiles.
It's important to note that sulfur dioxide can also react with other substances in the atmosphere, like oxygen, to form sulfuric acid (H₂SO₄), which is a stronger acid.
