The ideal gas law is a simple model that allows us to predict the behavior of gases in the world. It is a combination of the previous laws that we have studied (Boyle's, Charles', Avogadro's). Rather than simply looking at proportionalities, it relates pressure, volume, absolute temperature, and the number of moles quantitatively with a universal constant \(R\) that we call the ideal gas constant.
\[P\,V=nR\,T\]
The value for R will depend on what units you are using for the properties of the gas. The ideal gas law has many implications that will be discussed below. However, the most remarkable aspect is that the same model works quite well for all gases (N2, He, C3H8, ...).