Acoustic Behaviour of Cetylpyridinium Bromide (CPB) in Methanol

Abstract

Ultrasonic velocity measurement has been employed to obtain various acoustic parameters and the critical micelle concentration CMC (0.045 mo! m⁻³), which is found to be in good agreement with the one determined by conductance method (0.042 mol m⁻³), for methanolic solutions of cetylpyridinium bromide CPB at 313.15 K. The results show that there is a significant interaction between solute and solvent molecules in dilute solutions. The values for intermolecular free length L′_f computed from thermodynamic method given by Eyring and Hirschfelder, are in good agreement with those of L_f evaluated from ultrasonic data using Jacobson's relation. Several other parameters, viz. molecular radius r_m , space filling factor r_j (B/V) and collision factor S, have also been evaluated from collision factor theory CFT of Schaaffs.

Key Words:

• Ultrasonic velocity
• critical concentration