Features of dimerization equilibrium in hard-sphere fluids

We describe the deviations of the concentration of dimers from ideal behavior, which are connected with a change in the molar volume of liquid as a result of an elementary chemical reaction both within the spherical simplified model and taking into account the dumbbell-like shape of a dimer. A generalization of the model for a dimerizing hard-sphere fluid in the presence of a solvent with its own diameter value is considered. It is shown that with an increase in the particle size of the solvent, the nature of the concentration dependence of the enthalpy of mixing can vary from purely endothermic to alternating-sign with a pronounced exothermic effect at low and moderate content.