Consider the following gases, all at STP: Ne, SF_{6}, N_{2}, CH_{4}.

Which one has the highest total molecular volume relative to the space occupied by the gas?

We’re being asked **which has the highest total molecular volume relative to the space occupied by the gas.**

The** ideal gas theory**** does not consider the volume of the gas molecules** itself so we need to consider another theory that can account for like the **Van de Waals theory of gas.**

The **Van der Waals equation** is shown below:

$\overline{)\left(\mathbf{P}\mathbf{+}\mathbf{a}\frac{{\mathbf{n}}^{\mathbf{2}}}{{\mathbf{V}}^{\mathbf{2}}}\right)\left(\mathbf{V}\mathbf{-}\mathbf{n}\mathbf{b}\right){\mathbf{=}}{\mathbf{n}}{\mathbf{R}}{\mathbf{T}}}$

▪ **P** = pressure, atm

▪ **V** = volume, L

▪ **n** = # of moles, mol

▪ **R** = gas constant = 0.08206 (L∙atm)/(mol∙K)

▪ **T** = temperature, K

▪ **a** = polarity coefficient

▪ **b **= size coefficient

Van der Waals Equation

Van der Waals Equation

Van der Waals Equation

Van der Waals Equation