Understanding Sulphur Dioxide (SO₂)

Sulphur dioxide (SO₂) is a chemical compound formed by sulphur and oxygen. To determine its nature, we need to understand how it behaves when it reacts with water and what type of oxide it is.

Step 1: Recall the Definition of Acidic Oxide

An acidic oxide is an oxide that reacts with water to form an acid, and with bases to form a salt and water.

Step 2: Analyze the Reaction of SO₂ with Water

When sulphur dioxide is dissolved in water, it forms sulphurous acid (H₂SO₃). The chemical reaction is:

$SO 2 + H 2 O \to H 2 SO 3$

Since it produces an acid, this is a key property of an acidic oxide.

Step 3: Analyze the Reaction of SO₂ with a Base

Sulphur dioxide reacts with a base, such as sodium hydroxide (NaOH), to form a salt (sodium sulphite) and water. The reaction is:

$2 NaOH + SO 2 \to Na 2 SO 3 + H 2 O$

This neutralization reaction further confirms its acidic nature.

Final Answer

Based on its reactions, Sulphur dioxide (SO₂) is an acidic oxide.

Related Topics & Formulae

Types of Oxides:

Acidic Oxide: Oxides of non-metals that form acids with water (e.g., CO₂, SO₂, P₂O₅).
Basic Oxide: Oxides of metals that form bases with water (e.g., Na₂O, CaO).
Neutral Oxide: Oxides that show neither acidic nor basic properties (e.g., CO, NO, H₂O).
Amphoteric Oxide: Oxides that can act as both acidic and basic (e.g., Al₂O₃, ZnO).

Key Reaction Formulae:

General reaction of an acidic oxide with water:

$Acidic Oxide + H 2 O \to Acid$

General reaction of an acidic oxide with a base:

$Acidic Oxide + Base \to Salt + H 2 O$