Excess Molar Volume of 1-propanol+Aniline, +N-methylaniline, +N,N-dimethylaniline

Abstract

Densities of the systems, 1-Propanol(P)+aniline(A), 1-Propanol(P)+N-Methylaniline (NMA) and 1-Propanol(P)+N,N-Dimethylaniline(DMA) have been measured from 21°C to 50°C at an interval of 5°C. The excess molar volumes, V ^E, of the systems, P+A and P +NMA have been found to be negative for the whole range of composition. V^E of the system P+DMA has also been found to be negative, except in DMA-rich region where small positive excess volume is observed. The negative excess volume has been explained primarily in terms of strong specific interaction and size difference of unlike molecules. The magnitude of the negative excess volumes of these systems is of the order, P+A > P + NMA > P + DMA, which has been strongly influenced by steric effect due to CH₃ group attached to N-atom of NMA and DMA. In the highly rich region of DMA in P+DMA system the small positive excess volume is accounted for by the steric effect and breaking up of H-bond of 1-Propanol.