Viscosity and Thermodynamics of Viscous Flow of the Systems, 1-Propanol + Formamide, +N-Methylformamide, + N,N-Dimethylformamide

Abstract

Viscosities of the systems, 1-propanol(P) + formamide(F), + N-methylformamide (NMF), +N,N-dimethylformamide (DMF) have been measured in the temperature range 303.15-323.15 K with an interval of 5K. for all the systems viscosities and excess viscosities have been plotted against mole fraction of 1-propanol. Excess viscosities for the system P+ F have been found to be positive up to about 0.7 mole fraction of 1-propanol, followed by negative excess viscosities. the positive excess viscosities have been explained by the formation of P-F complex through H-bond, and the negative excess values have been interpreted by assuming that F is dissociated into smaller units in highly rich 1-propanol solution. for the systems, P + NMF and P + DMF, excess viscosities have been found to be negative for the whole range of composition. the negative values suggest that P and NMF are dissociated in their respective co-solvents. the interpretation put forward to account for the excess viscosities has been found to be consistent with the results of the excess thermodynamic activation parameters, ΔH^≠E ΔG^≠E and ΔS^≠E .

Key Words:

• Excess thermodynamic activation parameters for viscous flow
• formamide
• N-methylformamide
• N,N-dimethylformamide