Study on the Solubility of Gases in Liquids

Solubility is a property of a substance getting mixed with another substance completely or partially, depending upon the type of solvent and solute. A solution is made up of a mixture of a solute and a solvent. The solute is the dissolved substance that is present in a smaller amount in a solution. The solvent is the substance that is present in a higher amount than that of the solute, and it is the substance that dissolves the solute and forms the solution. 

The solubility of any substance is regulated and affected by temperature and pressure factors. The temperature factor affects all types of solubilities, whether solids or gases. Whereas the pressure factor only regulates the solubility of gases. 

Solubility of Gases in Liquids

The solubility of gases in liquid is the maximum amount of gas that can dissolve into a liquid. The solubility of gases in liquids is highly affected by the temperature, pressure, and also the nature of the solute and the solvent. 

The solubility of gases in liquids can thus be defined as the volume of the gas that can dissolve in a unit volume of liquid to form a saturated solution at room temperature or the experimental temperature and under one atmospheric temperature. 

Factors Affecting Solubility of Gases

The solubility of gases in liquids relies upon particular factors like- 

1. Mass of gas molecules: The higher the mass of the gas molecules, the lower the level of solubility. The solubility of a gas in liquids increases with the decrease in the molecular mass of the gases. The London and the Debye forces acting between the gas molecules increase with the increase in the molecular mass of the gas. So, for greater solubility, gases with lower molecular masses are preferred. 

1. Pressure: the solubility of gases in liquids increases with the increase in pressure. With the increase in pressure over the solution, the collision frequency between the gas molecules increases. This, in turn, allows the gas particles to get mixed with the solvent, i.e., the liquid, more easily. Higher pressure helps the gas molecules to be free and move around randomly. So, with the increase in pressure, the solubility of the gases in liquids increases. And also, with the decrease in pressure, the solubility decreases. 

The increase in pressure results in greater collisions of the gas particles with the surface, in turn, making the solubility process work more effectively. The more the particles come in contact with the surface, the more the gas molecules tend to mix with the solvent. So, the temperature increases the motion of the gas particles resulting in greater solubility.

The effect of the pressure factor on the solubility of the gases in liquid is represented by the Henry Law, which states, “In a dilute solution, the concentration of the dissolved gas is equal to the partial pressure of the solvent above the equilibrium state at a constant temperature.”

1. Temperature: the solubility of gases in liquids is found to decrease with the increase in temperature. With the increase in temperature, gases become less soluble. Whenever the gas molecules dissolve in liquids, they undergo a process called dissolution. Heat is generated during this process.

According to Charles Henry Law, the solubility of gases is inversely proportional to the temperature of the solution or solvent. The more the temperature rises, the less is the chance of solubility. With the increase in temperature, the kinetic energy of the gas molecules increases, resulting in the breakdown of the intermolecular force or bond that exists between the particles. This, in turn, results in the gas escaping from the solution. For example, the carbon dioxide content escapes faster in a carbonated drink when its temperature is high.

1. Presence of salt: whenever a dilute solution is made to make them soluble in the presence of any salt, the process is known as Salting out. Any dissolved gases, when dissolved in solutions, a salt electrolyte and a non-salt electrolyte are generally used to extract the gases from them—for example, Sucrose.  

The above factors affect the dissolving nature of the gases in liquids differently. Whenever the substances are bought under various conditions of physical factors like temperature, pressure, etc., the reaction of the molecules changes and affects the solubility accordingly. 

Conclusion:

Solubility is a physical factor that is affected and keeps on changing with the changing parameters. Generally, with the increase in pressure, the solubility increases. On the other hand, the solubility of gases in liquids decreases with the increase in temperature. So, the solubility of any substance in any medium solely depends upon the physical conditions under which they are made to mix and the amount of solute and solvent involved.