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A Review of Solubility of Gas in Liquid

Peter M. Williams, Nicola McDougal
  • Author
    Peter M. Williams

    Peter holds a Bachelor's degree in Microbiology and Biotechnology, and a Master's degree in Applied Microbiology. In addition, Peter has more than two years of experience in tutoring and writing academic materials for senior and junior schools, mainly in Sciences, Languages, and Humanities.

  • Instructor
    Nicola McDougal

    Nicky has taught a variety of chemistry courses at college level. Nicky has a PhD in Physical Chemistry.

Learn about gas solubility. Identify how pressure and temperature affect solubility of a gas, and see some applications of the solubility of gas in liquid. Updated: 02/18/2022

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What Is Gas Solubility?

A substance such as sugar, when mixed with water, results in a sweet mixture referred to as a solution. Any substance that dissolves in a liquid is known as a solute. A solute can be a solid, gas, or another liquid. The liquid into which a solute dissolves is referred to as a solvent. A mixture of a solute and a solvent forms a solution.

Therefore, any substance that dissolves in a solvent is said to be soluble. Insoluble substances do not dissolve in a solvent to form a solution. In addition, the amount of solute present in a given solvent or solution is termed as a concentration of a solution. A solution is said to be saturated when it can longer dissolve more of the solute, i.e., contains the maximum of the solute.

The ability of a solute to mix and form a solution with a solvent is termed solubility. Some substances do not mix to form a solution; thus are termed insoluble. The solubility of substances is affected by factors such as temperature, pressure, and the nature of a solute. The solubility of a substance is described as either soluble, slightly soluble, or insoluble.

Suppose a certain amount of gas dissolves in a liquid at a specific temperature to form a solution. In that case, this is termed gas solubility. Therefore, gas solubility can be defined as the ability of gas to dissolve in a solvent (liquid) to form a solution at a specific temperature.

Examples of Gases that Dissolve in Water

There are several gases that dissolve in water. In normal conditions, the amount of gas that dissolves in a solvent is nearly proportional to the pressure of the gas. Therefore, some of the gases are more soluble in water than others. Examples of gases that dissolve in water include:

  • Ammonia gas — This colorless gas with a pungent smell is the most soluble gas in water. It forms an alkaline solution.
  • Oxygen gas — This gas is also known to dissolve in water. Dissolved oxygen in water plays a vital role in supporting aquatic life.
  • Hydrogen chloride gas — This gas is very soluble in water. It forms a hydrochloric acid solution.
  • Carbon dioxide gas — This gas slightly dissolves in water to form a weak carbonic acid solution
  • Sulfur dioxide gas — This gas dissolves in water, forming a solution containing sulfurous acid.
  • Chlorine gas — This gas dissolves in water to form chlorine water.

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How Does Pressure Affect the Solubility of a Gas?

Pressure is one of the main factors that significantly affects the solubility of a gas in a liquid. Henry's law dictates the solubility of a gas in a liquid. Henry's law states that the solubility of a gas in a liquid is directly proportional/corresponds to the pressure of the gas over a solution.

Suppose the gas molecules in a solution were compressed by increasing the pressure. In that case, more room will be created for more gas molecules to dissolve in the solvent. In addition, the number of gas molecules above the solution will also increase, thus readily dissolving in the solvent, occupying the space created after an increase in pressure.

Therefore, the solubility of a gas in a liquid increases with an increase in pressure at a given temperature. Similarly, the solubility of a gas decreases with a decrease in pressure.

Examples of How Pressure Affects Solubility

How does pressure affect the solubility of a gas? An increase in pressure at a specific temperature will result in more gas dissolving in a solvent, while a decrease in pressure lowers the gas solubility rate in a liquid. For instance, in making carbonated drinks such as soda, more pressure is applied over the solute to increase the solubility of carbon dioxide in the liquid. An increase in pressure makes the gas molecules in the solute compress, thus creating more room for additional gas molecules. This results in a high solubility rate of carbon dioxide in the liquid. Therefore, as pressure increases, the solubility of gases in liquid also increases. This can be illustrated using Figure 1.


Figure 1: An increase in pressure increases the solubility of gas in liquid

Pressure vs. Gas Solubility in Liquid Graph


How Does Temperature Affect the Solubility of a Gas?

An increase in temperature decreases the solubility of a gas in a liquid. This can be explained using Le Chatelier's principle. This principle states that if the normal state of a system/reaction is disturbed by a variable such as a temperature, the system/reaction responds by adjusting its composition to counteract/act against the change of that variable. Therefore, a reaction that releases heat (exothermic) will cause the solubility of gas to decrease since the temperature will be rising.

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Frequently Asked Questions

How do we determine the solubility of gasses in water?

Three factors determine the solubility of gases in water. The temperature, pressure of the gaseous solute, and nature of the solvent and solute particles. High temperature reduces the solubility rate of gases in water. In addition, high pressure increases the solubility of gases in water. Lastly the chemical structure of a solute or solvent will influence the solubility of a gas in water due to the action of various forces of attraction between molecules.

Why does gas solubility decrease with temperature?

The gas solubility decreases with an increase in pressure due to the disturbance of a normal state of a system/reaction by a variable (temperature). As a result, the system/reaction readjusts itself to act against the increase in temperature by decreasing the solubility of a gas. This is known as Le Chateleir's Principle.

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