Surfactants Soaps and Detergents Aqueous Solutions Surface-Active Substances

4 SURFACTANTS (SOAPS AND DETERGENTS) AQUEOUS SOLUTIONS (SURFACE-ACTIVE SUBSTANCES) 

Surface tension of typical inorganic salt-water solutions (20°C)  

FIGURE 1.22 Change in surface tension of water on addition of inorganic salt (e.g., NaCl or KCl) or a soap. 

It is thus seen that even very small differences in snrface tension of these solutions indicate some significant characteristics that are unique for the system. These phenomena have very significant consequences in systems where these ions are present in connection with surfaces. One example is that in biological cells, the role of Na+ and K+ (and other cations) is significantly different (Birdi, 

Change in y with the addition of solute (equal molar concentration)  

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