The electrical conductance and viscosity of Nigerian traditional soaps in alcoholic media

Abstract

The electrical conductances and viscosities of Nigerian traditional soaps in alcohols have been measured. Potassium, sodium and potassium/sodium (50:1) soaps have been prepared from palm kernel oils using laboratory prepared reagent alkalis and their conductances have also been measured. While the conductances vary with the degree of purity of the soaps and the polarity of the solvents, the activation energy for conductance only varies with the change of solvents. The conductances of the laboratory prepared potassium soaps are higher than those of the sodium soaps, suggesting the metal ions to be the main charge carriers in solution. Plots of logarithm of conductivity against inverse temperature are linear for all the soaps in methanol and ethanol while such plots are non-linear in propan-1-ol in which the soaps are least soluble with lowest conductance values. However, the plot is linear for the laboratory prepared potassium soap in propan-1-ol. The conductivities of the commercial (traditionally prepared) soaps are found to be higher than those of the laboratory prepared ones, indicating the formation of soaps of many fatty acid constituents of palm kernel oil in the traditional process of soap preparation. The variations of the viscosities of the solutions with concentration, temperature and carbon chain length of the solvents are also discussed. The plots of log 10 η versus 1/ T for all the soap solutions are linear suggesting that the solutions are non-associated liquid systems in agreement with the conductance data. The variations of the activation energies obtained from these plots with concentration and molecular weights of the solvents are discussed. The viscosity data are also interpreted on the basis of Jones–Dole equation. The trend of the B-coefficient of this equation suggests that the soaps become less ideal with increase in the molecular weights of the alcohols. The erratic nature of the A-coefficient values is again related to the results of conductance measurement which indicate that the traditional method of soap preparation produces mixed soaps and that the soaps contain many trace metal ions.