Estimations of Dipole Moments, Molar Polarizability and Polarizability of Benzoic Acid and 4-Hydroxycoumarin

Estimation of electric dipole moments, molar polarizability and polarizability of benzoic

acid and 4-hydroxycoumarin were carried out. Standard solutions of the solutes were prepared in

double distilled solvents ranging from non-polar to solvents (acetic acid, ethanol, propan-2-ol,

chloroform and n-hexane). The refractive indices and the dielectric constants of the samples were

determined in these solvents. The refractive index was measured from Abbe refractometer which

measures at temperature range of 25-45 oC. The dielectric constant was derived from the refractive

index using the Debye equations. These two parameters (dielectric constant and refractive index) were

used to estimate the dipole moment and polarizability. The results showed different variations of the

dipole moments of the solutes as the solvent polarity increases from n-hexane to dichloromethane.

However, constant decrease of the dipole moments of all the molecules was observed in acetic acid.