Factors That Affect the Solubility of Gas in Liquid

Gas can be dissolved in liquids when the surrounding environment is conducive. Temperature and pressure both affect how gas dissolves into a liquid and how easily it can come out of solution. Knowing this can help you in everyday circumstances like avoiding a flat carbonated drink or determining how long you can stay down when scuba diving.

  1. Temperature

    • As temperature increases, the solubility of a gas will decrease. The reason for this is that as the temperature increases, heat energy is transferred to the solute gas molecules where it is converted to kinetic energy. As the liquid molecules start moving around, they move farther apart from each other and the gas then escapes the liquid more easily. An example of temperature affecting gas solubility is a power plant discharging hot water into a river. This allows dissolved oxygen in the water to escape and takes away the fish's supply of oxygen, resulting in fish deaths.

    Pressure

    • When the pressure over a liquid is increased, the solubility of the gas is increased. The reason for this is that as the pressure increases, more gas molecules strike the surface of the liquid to enter solution. A carbonated drink is a good example of a pressure affecting solubility. An unopened can of soda has almost pure carbon dioxide at a pressure greater than atmospheric pressure above it and carbon dioxide dissolved in it (the bubbles). When you open the drink, you decrease the pressure above the liquid as it returns to atmospheric pressure and the bubbles begin to come out of solution.

    Henry's Law

    • Henry's Law states "The solubility of a gas is directly proportional to the partial pressure of gas over a liquid." To simplify this: If the pressure above a liquid is twice as high then twice as many molecules will hit the liquid service over a given period of time. This is an important consideration in activities such as scuba diving where more gases are absorbed into human tissues when under pressure (depth). Divers should account for this when coming up to allow the absorbed gases to escape their bodies or risk decompression sickness.

    Other Factors

    • Different gases have different solubility's in different liquids. For example, carbon dioxide is 22 times as soluble as oxygen when in contact with the plasma of a human body. You must account for the different solubility's of gases when applying Henry's law.