Abstract: Excess volumes have been measured by means of a continuous dilution dilatometer or a vibrational tube densimeter for both tetrachloromethane and trichloromethane+N,N-dimethylformamide (DMF), +N,N-dimethylacetamide (DMA), +N-methylpyrrolidone(NMP), +γ-butyroIactone(γ-BL) , +dimethysulfoxide(DMSO), at 298.15 K V~E values are negative over the entire range of composition for all systems except (trichloromethane + dimethylsulfoxide) which exhibits a sigmoid curve with negative values in the trichloromethane rich region. |V_(min)~E| values of the two series decrease in the order NMP>γ-BL>DMF≈DMA?DMSO. The results are interpreted in terms of forming charge-transfer complexes between tetrachloromethane and Lewis bases, and forming hydrogen-bonding associations between trichloromethane and Lewis bases respectively.

Key words: Lewis bases, Tetrachloromethane, Trichloromethane, Excess volumes, Continuous dilution dilatometer