Gas Solubility and Temperature



 

Learning Objective

  • Recall the relationship between gas solubility and temperature

Key Points

    • Gases dissolved in water become less soluble with increasing temperature.
    • Gases dissolved in organic solvents become more soluble with increasing temperature.
    • Dissolved oxygen in water is important to the survival of fish, so increasing temperature (and therefore less dissolved oxygen in water) can cause problems for fish.

Term

  • solubilityThe amount of a substance that will dissolve in a given amount of a solvent to give a saturated solution under specified conditions.

Several factors affect the solubility of gases: one of these factors is temperature. In general, solubility of a gas in water will decrease with increasing temperature: colder water will be able to have more gas dissolved in it.

Solubilities of Gases in WaterMethane, oxygen, carbon monoxide, nitrogen, and helium all have different solubilities in water, but all of them become less soluble with increasing temperature.

Consequences of Gas Solubility Temperature Dependence

When the temperature of a river, lake, or stream is raised abnormally high, usually due to the discharge of hot water from some industrial process, the solubility of oxygen in the water is decreased.

Because fish and other organisms that live in natural bodies of water can be sensitive to the concentration of oxygen in water, decreased levels of dissolved oxygen may have serious consequences for the health of the water’s ecosystems. In severe cases, temperature changes can result in large-scale fish kills.

Gas Solubility In Organic Solvents

The trend that gas solubility decreases with increasing temperature does not hold in all cases. While it is in general true for gases dissolved in water, gases dissolved in organic solvents tend to become more soluble with increasing temperature.

There are several molecular reasons for the change in solubility of gases with increasing temperature, which is why there is no one trend independent of gas and solvent for whether gases will become more or less soluble with increasing temperature.