Chemical equilibrium in supercritical fluids: Solvent effects on the dimerization equilibrium constant

Dimerization equilibrium between two dilute solutes in a supercritical solvents was studied. The equilibrium constant was calculated using nonlocal hypernetted chain integral equation theory. The constant showed a characteristic three regime density dependence along near-critical isotherms. The three regimes were explained in terms of energy-dominated low-density, desolvation-dominated medium-density, and entropy-dominated high-density regions.