ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2014, Vol. 88, No. 7, pp. 1255–1264. © Pleiades Publishing, Ltd., 2014. 1255 1 INTRODUCTION In the recent years many works have been done to study the molecular interactions in the mixtures of alkanols with other components by considering differ- ent parameters like density, viscosity, ultrasonic veloc- ity, surface tension etc. The excess property study has been used for the purpose of designing equipment in heat transfer, fluid mechanics and process calcula- tions. In the present work the mixture of pentan-1-ol (1) + nitrobenzene (2) is studied. The objective of our work is to measure the density, viscosity, ultrasonic velocity at temperatures 303.15, 308.15, and 313.15 K and 0.1 MPa. Amyl alcohols are used as industrial solvents. Also it is used as perfume ingredient and in synthesis of fruit essence and intermediate in amyl acetate production. Many works have been done on amyl alcohol to study its physical properties [1–7]. Nitrobenzene is mainly used in the preparation of aniline. Also it is used as a solvent and raw material for organic synthesis. EXPERIMENTAL SECTION Materials and Methods All the solvents used were of analytical grade and obtained from Merck (India), Bombay and Sisco 1 The article is published in the original. Research Laboratories (India). These chemicals have been purified before use [8, 9]. The purity of the sol- vents was verified with the literature values, given in Table 1 [1–3, 10, 11]. Ostwald viscometer calibrated with water and ben- zene was used for measuring the viscosity of all liquids at temperatures [12] v = (at) – (b/t). (1) The density of the liquids was measured with Ost- wald-Sprengal type 25 cm 3 pyknometer. The ultra- sonic velocity of sound for all liquids was measured using ultrasonic interferometer (Mittal Enterprises, New Delhi), operating at 2 MHz with an accuracy of ±1 m/s. All the experiments were carried out in a ther- mostatically controlled constant temperature water bath of reproducibility ±0.1°C. The relation used for the calculation of ultrasonic velocity [13, 14] is u = (λ/2) av × 2n, (2) where λ is the wavelength in m, and n is the frequency in Hz. MODEL SECTION (A) For thermo physical property: —Dynamic viscosity was calculated by using the equation , (3) η v ρ = OTHER PROBLEMS OF PHYSICAL CHEMISTRY Effect of Temperature and Concentration on Density, Viscosity and Ultrasonic Velocity of the Pentan-1-ol + Nitrobenzene Mixtures 1 S. K. Bindhani a , G. K. Roy a , Y. K. Mohanty a , and T. R. Kubendran b a Department of Chemical Engineering, Gandhi Institute of Engineering and Technology, Gunupur–765022, Rayagada, Odisha, India b Department of Chemical Engineering, A. C. Tech., Anna University, Chennai–600025, India *e-mail: santubindhani@gmail.com Received September 8, 2013 Abstract—Density, viscosity and ultrasonic velocity values for pentan-1-ol (1) + nitrobenzene (2) mixtures were measured at temperatures of 303.15 to 313.15 K. The new equations have been developed for viscosity and ultrasonic velocity by the use of statistical software Design Expert. The excess values like excess molar volume, viscosity deviation and ultrasonic velocity deviations have been calculated from density, viscosity and ultrasonic velocity respectively. The excess values were correlated using the Redlich–Kister polynomial equa- tion to obtain their coefficients and standard deviations. Keywords: molecular interaction, viscosity, ultrasonic velocity, pentan-1-ol. DOI: 10.1134/S003602441407005X