Dipolemeter

Dipolemeter   

Objective: Determination of dielectric constant of non aqueous liquid at different concentration and hence determination of Dipole Moment (e.g. of Nitrobenzene etc.)

Theory: Dipole Meter is an adaptable instrument that is used for measuring the dielectric constant of non-polar liquids. In the equipments a particular circuit has been developed for audio oscillator that produces stabilized wave. In this experiment dielectric cell is standardized using reference liquid having known dielectric constant by immersing the dielectric cell assembly in to reference Liquid. Then experimental liquid whose dielectric constant has to be determined is taken and assembly is immersed into liquid, resulting in change in oscillation frequency. From resulting shift, capacitance of cell in unknown liquid is calculated (CX). Dielectric Constant of unknown liquid is calculated using relation:

where Capacitance of Air,Capacitance of  standard liquid, Capacitance of  test liquid and dielectric constant of standard liquid

Solution of polar molecule having molecular wt. with non-polar solvent having molecular wt. in different concentrations, is considered. Molar Polarization of the mixture is obtained by relation

               

where k is dielectric constant of the solution having molefraction  of polar molecule and mole fraction  of  non polar solvent and  is the density of the mixture.

A graph between  and is obtained  
          

The dipole moment  is calculated using relation

           
Where T is absolute temperature,is molar polarization of  non-polar liquid and is molar polarization of non polar liquid.

The apparatus consists of :