The Ideal Gas Law

The ideal gas law describes the state of an ideal gas. Most gas however are not actually ideal and don't behave exactly as the ideal gas law would predict (gas at high temperature or pressure), however the ideal gas law is useful for a range of applications and a very good approximation of how a gas will behave and so worth studying in detail. The ideal gas law is

PV = nRt or PV= NkT

These two forms for the ideal gas law are actually equivalent. The first form deals with moles of the gas (n) where as the second (N) deals with the number of molecules. Chemists prefer to work with moles where as physicist use molecules. The other variables are: P = Pressure, V = Volume, R = Gas Constant and finally k = Boltzmann Constant

Properties of the Ideal Gas Law

Recall that the ideal gas law is defined as : PV = NkT

If the volume and the number of atoms is held constant they can be extracted into a constant (A)

P = (NkT)/V = AV

Rearranging the formula in this manner can tell a new property about gases.

P ά T

In words this means that the pressure is proportional to the temperature the constant can be dropped in this sort of relation because it is just describing the rate at which each increase. Recall that the equation of a line is

x = ay + b (a and b are some constants)

Pressure and volume have a linear relationship, meaning that the equation relating them is similar to the equation of a line. Simply set a = A and b = 0, this tells us that as the pressure increases/decreases the temperature does the same in a similar manner and visa versa.