Under Which Conditions Are Gases Most Soluble in Water?

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Solubility of gases in water is affected by pressure and temperature. Increasing the pressure increases the solubility of the gas in water. Decreasing the temperature also increases gas solubility in water.

The effect of pressure on gas solubility in water is given by Henry’s law, which states that the solubility of the gas in a liquid is directly proportional to the pressure of the gas above the liquid. When the pressure is low, the gas molecules tend to stay in the gas above the liquid rather than dissolving into the liquid. However, when the pressure of is increased, the gas molecules have less space to move around in above the liquid and are more likely to enter the solution. Carbonated beverages such as soda are packed under high pressure to allow the gases to remain dissolved in the liquid.

The effect of temperature on gas solubility can be explained by Le Chatelier’s principle, which states that when a system under equilibrium is placed under stress, the equilibrium will shift in a way that relieves the stress. Gas molecules above the surface of a liquid are in equilibrium with the liquid, which means the number of gas molecules entering the liquid is equal to the number of gas molecules leaving the liquid. Whenever a gas molecule dissolves in liquid, a small amount of heat is released. According to Le Chatelier’s principle, decreasing the temperature should shift the equilibrium such that more gas molecules dissolve in the liquid, thus increasing gas solubility.