Viscosities and Densities of Binary Mixtures of Hexane with 1-Chlorohexane between 293.15 K and 333.15 K Mikhail F. Bolotnikov* and Yurij A. Neruchev Department of General Physic, Kursk State University, Kursk, Radishcheva 33, Russia The density and viscosity values of binary mixtures of hexane with 1-chlorohexane have been measured as a function of composition and temperatures between 293.15 K and 333.15 K. The estimated uncertainties are less than (1 × 10 -4 g‚cm -3 for density and (0.5% for viscosity. Viscosity deviations Δη were fitted by the Redlich-Kister equation. Introduction The thermophysical properties of binary mixtures con- taining alkanes with 1-chloroalkanes and 1-iodoalkanes with polar molecules of the type (polar group)-(CH 2 ) n - (CH 3 ) have been extensively studied with the aim of a better understanding of the intermolecular interactions. A detailed understanding of the effect of the presence of the chlorine (-Cl) or iodine (-I) groups in the mixture on the excess thermodynamic properties and the behavior of haloalkanes in mixtures with alkanes is important from both practical and fundamental viewpoints. On the other hand, a knowledge of the thermophysical properties of nonelectrolyte solutions such as viscosity and density will be helpful for the chemical industry for the design of processes of mass transfer, heat transfer, and fluid flow. In this work, the viscosity and density of the binary mixtures hexane + 1-chlorohexane were measured at temperatures from 293.15 K to 333.15 K. The excess molar volume of this mixture was found in the literature 3 at 298.15 K. Our literature survey does not include experi- mental data on the viscosities of the mixture chosen for this study. In works 6,7 on viscosity devoted to study of binary liquid mixtures of n-alkanes with 1-chloroalkanes, the mixture researched by us is absent. Experimental Section Materials. Hexane, 1-chlorohexane (mole fraction, >0.99) was supplied from Sigma-Aldrich Ltd. All chemicals were partially degassed and dried over Fluka 0.4 nm molecular sieves. The purity of the products was checked by gas chromatography (GC). The purity for hexane and 1-chlo- rohexane was 99.7 and 99.3 mol %, respectively. The mixtures were prepared by mass, with a precision of (5 × 10 -5 g. The uncertainty in the mole fraction is less than 1 × 10 -4 . All molar quantities are based on the IUPAC relative atomic mass table (IUPAC, 1986). 4 Measurements. Densities were measured with a Ost- wald-Sprengel type pycnometer, with a capacity of ap- proximately 50 cm 3 . The uncertainty of the density mea- surements was estimated to be (3 × 10 -5 g‚cm -3 . The values of composition reported in Tables 2-4 are ap- proximated up to three digits. The kinematic viscosities of the pure liquids and liquid mixtures were measured between 293.15 K and 333.15 K with a step of 5 K, and atmospheric pressure was determined with a calibrated Ubbelohde suspended level viscometer of 0.56 mm diam- eter. The accuracy of the flow time measurement was (0.01 s. Flow time was taken as an average of 10 measurements. The viscometer was always kept in a vertical position in a water thermostat controlled to (0.01 K. The following equation was used to calculate the viscosities: where t is the flow time, η is the absolute viscosity, F is the density, and A and B are the viscometer constants, determined by the calibration fluids. The viscometers were calibrated by using high-purity toluene, heptane, and nonane at the working temperatures. The estimated error of the viscosity measurements was (0.5%. Experimental values of densities and viscosities for the pure liquids at different temperatures were compared with those found in the literature and were in fairly good agreement, as shown in Table 1. Results and Discussion The measured values of density (F) and viscosity (η) along with the values of deviations in viscosity (Δη) calculated as described below for the binary mixtures hexane (1) + 1-chlorohexane (2) as a function of mole fraction x 2 are given in Table 2, for temperatures from 293.15 K to 333.15 K. The deviations in viscosity are calculated by using the equation Table 1. Comparison of Experimental Densities, G, and Kinematic Viscosities, ν, with Literature Data for Pure Liquids at Different Temperatures F/(kg‚m -3 ) 10 6 × ν/(m 2 ‚s -1 ) liquid T/K this work literature (ref) this work literature (ref) hexane 293.15 659.44 659.40 (8) 0.4796 0.4748 (11) 298.15 654.93 654.89 (1) 0.4635 0.4580 (12) 654.8 (12) 303.15 650.36 650.2 (12) 0.4480 0.4523 (10) 308.15 645.74 645.86 (9) 0.4331 0.4297 (12) 323.15 631.61 631.5 (12) 0.3930 0.3922 (10) 333.15 621.95 621.9 (11) 0.3711 0.3691 (10) 621.8 (12) 1-chlorohexane 298.15 873.75 873.38 (2) 0.4213 η F ) At - B t (1) Δη ) η - (x 1 η 1 + x 2 η 2 ) (2) 739 J. Chem. Eng. Data 2003, 48, 739-741 10.1021/je034002l CCC: $25.00 © 2003 American Chemical Society Published on Web 04/18/2003