Charged Lipid Monolayers on Liquid Surfaces

It is also seen that the following equation will be valid for this system  

This is the form of the Gibbs equation for an aqueous solution containing three different ionic species (e.g., R Na Cl). Thus, the more general form would for solutions containing i-number of ionic species as 

At 25°C, for uni-univalent electrolytes one gets the following (Adamson and Gast, 1997 Birdi, 2009)  

This relates the potential charge of a plane plate condenser to the thickness 1/k. The expression for 

The quantity (kT) is approximately 4 x 10 erg at ordinary room tanperature (25°C), and (kT/e) = 25 mV. The magnitude of Hi can be estimated from monolayer studies at varying pH. At the iso-electric pH, the magnitude of 11 will be zero (Birdi, 1989). These II versus A isotherms data at varying pH subphase have been used to estimate Hi in different monolayers. 

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