Partial pressures

In a mixture of gases, perfect or real, the partial pressure of an individual gas defined as:

p_i = Patial pressure
p = Total pressure
x_i = mole fraction of the gas

n_i = moles of individual gas

n = total moles of all gases in the mixture

Note the following:

- Each mole fraction is between 1 and 0
- All the mole fractions in a mixture add up to one
- Total pressure is the sum of each partial pressure

These can also been understood intuitively by plugging in numbers.

If the gas is perfect, then Dalton's law applies:

The pressure exerted by a mixture of gases is the sum of the pressures that each one
would exist if it occupied the container alone.