ABSTRACT
The ideal gas law assumes that particles are zero-dimensional point masses that do not interact with one another. Real particles, regardless of their state, do have both dimensions and interact with one another. The van der Waals equation is one of several equations that accounts for the behavior of real gases by including two correcting variables a (which accounts for particle–particle interactions) and b (which accounts for particle size). In this chapter, the a and b values are used to explore intermolecular forces (IMFs). A plot of a as a function of b shows a linear relationship. As molecules increase in size, their IMFs increase. This is the fundamental IMF: dispersion. Other IMFs – dipole–dipole interactions (which require polar bonds) and hydrogen bonds (which require an O–H, N–H, or F–H in the molecule) – can add to the strength of particle–particle interactions. Differences in IMFs are correlated with differences in physical properties (boiling point, solubility) of atoms and molecules.
