Q6. Consider the graph below reporting surface tension values versus concentration of added
surfactant RCI, where R is a long alkyl chain with a positively charged head group, in an aqueous
solution at 25quot; C. The two data seta are collected with different amounts of dissolved salt (pure water
and excess KCI). (2 marks)
(a) Using the data below, estimate the minimum surface area per surfactant molecule adsorbed at
the air/water interface at 5*10 M surfactant’s concentration in pure water.
(b) Is the surface area per molecule in salt solution higher or lower than that in pure water? Briefly
explain the physico-chemical reason for your answer.
Surface Tension, mN/m