Concentration Gradients in Nitroethane + 3-Methylpentane near the Liquid-Liquid Critical Solution Point

Abstract

Precise measurements of density profiles in the system nitroethane + 3-methylpentane near the critical solution point demonstrate that concentration gradients form rapidly, but true equilibrium is not achieved even after long times. The data are in qualitative agreement with computer calculations of the behavior of a critical mixture in a gravitational field which show that the initial gradients form by sedimentation. Thus, effects due to gravity may affect careful experiments in critical mixtures.