Density and Viscosity Analysis of 3-Methyl-3-pentanol and C3–C6 1-Alkanols: Employing Free Volume Theory for Viscosity Insights

This study conducts an examination of the thermophysical properties of 3-methyl-3-pentanol alongside a series of short-chain alcohols, ranging from C₃ to C₆ alcohols (1-propanol through 1-hexanol), across a temperature spectrum from 293.15 K to 323.15 K. The focus of this investigation lies on the assessment of excess molar volumes and deviations in viscosity, uncovering a systematic enhancement in negative excess molar volumes as the length of the alkyl chain increases. Concurrently, viscosity analyses indicate deviations from ideality, showcasing a positive trend that diminishes with the extension of the alkyl chain. This suggests significant molecular interactions occurring between 3-methyl-3-pentanol and the examined alcohols. Further, this research incorporates the free volume theory (FVT) to draw correlations between the viscosities of both pure substances and their binary mixtures. Remarkably, the FVT demonstrates a close congruence with the experimental findings, exhibiting a maximum deviation of 2.23 % in the mixture of 3-methyl-3-pentanol and 1-hexanol. Such findings underscore the precision and utility of the FVT in elucidating the thermophysical behaviors of these mixtures, thus advancing our comprehension of their intricate molecular interactions.