Electrosorption of 1-butanol and 2-butanol at a constant chemical potential of the base electrolyte: Effect of solute bulk activity on the adsorbate molecular coarea

The adsorption of l-butanol and 2-butanol was studied at an uncharged mercury-saturated K2SO4 aqueous solution interface. The rigorous procedure was employed in which the electrolyte activity was held constant and the interfacial tension was measured as a function of alcohol bulk activity and the potential difference between the mercury and a mercury - mercurous sulfate reference electrode containing the same solution as being investigated. The alcohol activities were measured by a gas chromatographic technique. In each case, the pi versus ln alpha(A) CUTVe was characterized by two linear portions. The molecular coareas resulting from the linear portions at intermediate and high activities were respectively 29.5 and 25.1 Angstrom(2) for 1-butanol and 30.4 and 25.6 Angstrom(2) for 2-butanol. The coarea of 25 Angstrom(2) obtained for 1-butanol is characteristic of condensed layer formation at the mercury-solution interface.