the lowestgattainable. Consequently, it is better to relate surface activity to
the concentration at whichPhas half its maximum value. Two of such
concentrations are indicated in the figure, and it follows that their
FIGURE10.6 Aqueous solutions of sodium soaps of normal fatty acids of various
chain length (number of C-atoms indicated). (a) surface tensiong(N?m^1 ) against
concentrationcin solution. (b) Calculated surface excessG(mol?m^2 ) against
concentration.