Eur. Phys. J. E (2009) 30: 19-26
https://doi.org/10.1140/epje/i2009-10496-4

Regular Article

Concentration and temperature dependence of the refractive index of ethanol-water mixtures: Influence of intermolecular interactions

¹ Instituto de Ciencia de Materiales de Madrid (C.S.I.C.), Campus de Cantoblanco, E-28049, Madrid, Spain
² Laboratoire de Physique des Matériaux, University of Luxembourg, 162a avenue de la Faïencerie, L-1511, Luxembourg, Luxembourg
³ Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condesada, C-III, Universidad Autónoma de Madrid, E-28049, Madrid, Spain

^* e-mail: rjimenez@icmm.csic.es

Received: 23 April 2009
Accepted: 15 July 2009
Published online: 4 September 2009

Abstract

The temperature and concentration dependence of the refractive index, n _D(x, T) , in ethanol-water mixtures agrees with previous data in the ethanol-rich concentration range. The refractive index versus concentration x determined at 20 ^° C shows the expected maximum at about 41 mol% water (22 mass% water). The temperature derivative of the refractive index, dn _D /dT, shows anomalies at lower water concentrations at about 10 mol% water but no anomaly at 41 mol% water. Both anomalies are related to intermolecular interactions, the one in n_D seems to be due to molecular segregation and cluster formation while the origin of the second one in dn _D /dT is still not clear.