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The Ideal Gas Law

The Ideal Gas Law

If you only glean one scrap of knowledge from this SparkNote, make sure that it is the ideal gas law equation:

PV = nRT    

This is the meat and potatoes of gases. With it, you will be able to solve almost any gas equation involving the pressure, volume, amount, and temperature of a gas.

Before we jump in, though, we need to get some basics down. The first two sections of this topic lay the foundation for the ideal gas law. Section one introduces Boyle's law and the manometer. Both measure the volume and pressure of a gas. Section two introduces Charles' law and Avogadro's law. Charles' law relates the temperature and volume of a gas. Avogadro's law relates the quantity a gas and its volume.

Boyles', Charles', and Avogadro's laws combine to form the ideal gas law, which is the uber law of gases. In the third section you'll see why. The ideal gas law can be manipulated to explain Dalton's law, partial pressure, gas density, and the mole fraction. It can also be used to derive the other gas laws. In short, it will satisfy most of your gas-based needs.

Let us address one caveat before we begin. The ideal gas law is an ideal law. It operates under a number of assumptions. The two most important assumptions are that the molecules of an ideal gas do not occupy space and do not attract each other. These assumptions work well at the relatively low pressures and high temperatures that we experience in our day to day lives, but there are circumstances in the real world for which the ideal gas law holds little value. With this in mind, let us begin.