Factors Affecting Gas Dissolution in Water

The amount of a specific gas that dissolves in water is influenced by several environmental factors. Understanding these factors is key to explaining gas solubility.

Gas Solubility (i)

Each gas has an intrinsic solubility in water, representing the maximum amount that can dissolve under specific conditions. This is a fundamental property.

Partial Pressure (ii)

According to Henry's Law, the amount of gas dissolved is directly proportional to its partial pressure above the water. Higher pressure forces more gas molecules into the water.

Mathematically, Henry's Law can be represented as:
$P = k \cdot x$
Where '$P$' is the partial pressure of the gas, '$k$' is the Henry's law constant, and '$x$' is the mole fraction of the gas in the solution (representing the amount dissolved).

Water Temperature (iii)

Generally, the solubility of gases in water decreases as the temperature increases. Warmer water molecules have more kinetic energy, making it easier for dissolved gas molecules to escape into the atmosphere.

Salt Levels (iv)

The presence of dissolved salts, or salinity, affects gas solubility. Increasing salt concentration typically lowers the solubility of most non-polar gases in water, a phenomenon often referred to as the 'salting out' effect.

Conclusion

Since all four listed factors—solubility, partial pressure, temperature, and salt levels—influence the amount of a gas dissolved in water, the correct answer includes all of them.