17. The solubility of gases in water depends on their interaction with water molecules, Four gases i.e. carbon dioxide, oxygen, sulphur dioxide and ammonia are dissolved in water. In terms of their solubility which of the following statements is correct?

    (1) Ammonia >Oxygen>Sulphur   dioxide>   Carbon dioxide
    (2) Oxygen>Carbon    dioxide>Sulphur    dioxide     > Ammonia
    (3) Sulphur   dioxide>Oxygen>     Ammonia>     Carbon dioxide
    (4) Ammonia>Sulphur    dioxide>    Carbon     dioxide> Oxygen

Solubility of Gases in Water: Which Gas Dissolves the Most?

Understanding Gas Solubility in Water

The solubility of a gas in water is based on its capacity to interact with water molecules by intermolecular forces such as hydrogen bonding and dipole interactions.

Factors Affecting Gas Solubility

Polarity – More polar gases dissolve more in water.

Hydrogen Bonding – Gases that are capable of hydrogen bonding are more soluble.

Temperature & Pressure – Increased pressure raises solubility (Henry‘s Law), whereas increased temperature lowers gas solubility.

Solubility Order of Given Gases
Let us examine the four gases according to their chemical characteristics:

1. Ammonia (NH₃) – Most Soluble ✅
Strongly polar and hydrogen bonds with water.

Highly soluble because it has strong intermolecular forces.

2. Sulfur Dioxide (SO₂) – Moderately Soluble
Polar molecule that associates with water via dipole forces.

Can partially ionize in water, creating sulfite and bisulfite ions, which enhances solubility.

3. Carbon Dioxide (CO₂) – Less Soluble
Slightly polar, but will not hydrogen bond strongly with water.

Solves by creating carbonic acid (H₂CO₃), but the reaction is restricted.

4. Oxygen (O₂) – Least Soluble
Nonpolar and does not get involved significantly with water.

Solves in water only because of weak dispersion forces.

Correct Order of Solubility:
Ammonia > Sulfur Dioxide > Carbon Dioxide > Oxygen

✅ Right Answer: (4) Ammonia > Sulfur Dioxide > Carbon Dioxide > Oxygen

Significance of Solubility of Gases in Water

1. Environmental Significance
The solubility of CO₂ has an impact on ocean acidification.

SO₂ dissolves in rainwater, which gives rise to acid rain.

2. Biological Systems
The solubility of oxygen is important for aquatic ecosystems.

The solubility of ammonia affects nitrogen cycles.

3. Industrial Uses
Ammonia and SO₂ are employed in chemical reactions because of their high solubility.

The solubility of CO₂ is important in drinks such as soda.

Conclusion
The solubility of gases in water depends on the polarity and compatibility of the gases with water molecules. Ammonia is most soluble, followed by sulfur dioxide, carbon dioxide, and oxygen. Solubility of gases is an important concept in chemistry, biology, and environmental science.