Determination of Stability Constants of Charge Transfer Complexes of CycloAlkanones with Tetrachloroethylene in n -Hexane Solutions by Ultrasonic Method.

The ultrasonic velocity ( U ), density (ρ) and viscosity (η) of solutions containing equimolar concentration of four cycloalkanones (cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone) and Tetrachloroethylene (TCE) in n -hexane solutions have been measured at five different temperatures in the range 293-313 K. Acoustical parameters such as adiabatic compressibility (β), Rao constant (R), absorption coefficient (α/ f 2 ), free energy of activation (Δ G *), internal pressure (π i ), cohesive energy (CE), free volume ( V f ), molecular interaction parameter with respect to ultrasonic velocity ( X u ), density ( X ρ ), and viscosity ( X η ) were calculated from the experimental data. Formation constant ( K ) values of the charge transfer (CT) complexes have been evaluated using a modified Bhat equation. Thermodynamic parameters such as free energy change (Δ G ), enthalpy change (Δ H ), and entropy change (Δ S ) for the formation of these complexes are computed from the variation of formation constant values with temperature. The stability constants of the charge transfer complexes formed between four cyclicketones and TCE correlate satisfactorily with polarisability (α), and ionization potential (IP) values of the ketones. [ABSTRACT FROM AUTHOR]