Excess molar volume of 1-propanol plus aniline, +N-methylaniline, +N,N-dimethylaniline

Densities of the systems, 1-Propanol(P)+aniline(A), 1-Propanol(P)+N-Methyla niline (NMA) and 1-Propanol(P)+N,N-Dimethylaniiine(DMA) have been measured from 21 degrees C to 50 degreesC at an interval of 5 degreesC. The excess m olar volumes, Yes, of the systems, P-I-A and P+NMA have been Found to be ne gative for the whole range of composition. I of the system P+DMA has also b een found to be negative, except in DMA-rich region where small positive ex cess volume is observed. The negative excess volume has been explained prim arily in terms of strong specific interaction and size difference of unlike molecules. The magnitude of the negative excess volumes of these systems i s 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 h ighly rich region of DMA in P+DMA system the small positive excess volume i s accounted for by the steric effect and braking up of H-bond of 1-Propanol .