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What is Dissolved Gas?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Dissolved gas is a situation which occurs when a gas becomes dissolved in another solute. People often think specifically of a gas-liquid mixture when they think of dissolved gases, but gases can also dissolve in other gases, as in the case of air. Gases may also be dissolved in solids, as in seen in the trace impurities which can be caused in metals when gases are introduced during the casting process.

In order for gas to dissolve in a liquid, it usually needs to be subjected to pressure and held under pressure to remain dissolved. If the pressure is reduced, the gas will start to precipitate out of the liquid. With solids, dissolved gases occur when there is pressure which traps the gas inside, and sometimes the gases precipitate out and form bubbles inside the solid; bread, for example, contains numerous bubbles formed by carbon dioxide released by yeast inside the bread.

Divers can experience "the bends" if they ascend from a dive too quickly.
Divers can experience "the bends" if they ascend from a dive too quickly.

In medicine, dissolved gas measurements are sometimes taken to monitor patient health. Healthy human blood has trace amounts of several gases, including oxygen and nitrogen. If these gases are out of balance, it can indicate that the patient has a health problem. Dissolved gas is also an issue when humans are transitioning from high pressure to low pressure environments, as seen when people rise too quickly during a dive and experience “the bends” as the dissolved nitrogen in their blood is released too quickly.

The anaesthesiologist is tasked with selecting the correct dissolved gases and dosage needed for each patient.
The anaesthesiologist is tasked with selecting the correct dissolved gases and dosage needed for each patient.

Anesthesiologists also work with dissolved gases. When they deliver anesthesia to patients under general anesthesia, they must blend gases appropriately to keep the patient sedated and to provide the patient with oxygen. This is done by adjusting an anesthesia machine in response to the patient's performance under anesthesia.

Dissolved gas measurements are also used in water quality assessment. Water naturally contains some gases, and interruptions in the normal balance of gases may be indicators that there is a water quality problem. Sites like dams may have monitors in the water continuously to measure the gases. Gas monitoring is also used in aquarium management.

Healthy human blood has trace amounts of several gases, including oxygen and nitrogen.
Healthy human blood has trace amounts of several gases, including oxygen and nitrogen.

People analyzing unknown samples may use a dissolved gas measurement to gather data about the sample and its origins. Such data can be useful for everything from identifying samples of liquids taken at a crime scene to conducting studies on natural phenomena. Several types of laboratory equipment can be used to determine the level of gases in a solution and to identify which gases are involved.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllTheScience researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllTheScience researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

anon280395

Is a gas dissolved in a liquid still a gas, or does it change to the liquid state?

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    • Divers can experience "the bends" if they ascend from a dive too quickly.
      By: eothman
      Divers can experience "the bends" if they ascend from a dive too quickly.
    • The anaesthesiologist is tasked with selecting the correct dissolved gases and dosage needed for each patient.
      By: uwimages
      The anaesthesiologist is tasked with selecting the correct dissolved gases and dosage needed for each patient.
    • Healthy human blood has trace amounts of several gases, including oxygen and nitrogen.
      By: Levi Lenaerts
      Healthy human blood has trace amounts of several gases, including oxygen and nitrogen.
    • Anesthesiologists work with dissolved gases.
      By: maska82
      Anesthesiologists work with dissolved gases.
    • Anesthesia is used to induce a state of deep sedation, but once the procedure is done, the anesthesiologist wants the patient to wake up quickly.
      By: Andres Rodriguez
      Anesthesia is used to induce a state of deep sedation, but once the procedure is done, the anesthesiologist wants the patient to wake up quickly.