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Chapter 2  Gas Solutions

It is odd to think of gas mixtures as solutions but they are indeed homogenous mixtures composed of components all in the same phase.

We often talk of the solubility of solids in liquid solvents.

There is an equivalent quantity for gas phase solutions that involves the solubility of liquids in the gas phase.

The vapor pressure is the "solubility" of a liquid in the gas phase.

We experience when the limit of this solubility is reached when the weather conditions result in 100% relative humidity and water starts precipitating out of the gaseous solution as dew or fog.

How soluble a liquid is in air, the vapor pressure, is dependent on the temperature much like sugar dissolves in hot water better than cold water.

The higher the temperature, the more water vapor the air can hold before it becomes saturated (i.e. relative humidity = 100%).

Given a certain amount of water vapor in the air, we can quantify that amount noting the relative humidity or by noting the dew point, the temperature at which the temperature would have to fall for the relative humidity to become 100%, any further below that creating a supersaturated gaseous solution of water which would cause the formation of dew, or fog, as the water precipitates.

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