The qualitative sketches given show the variation of surface tension with molar concentration of thr

Question

The qualitative sketches given show the variation of surface tension with molar concentration of three different aqueous solutions at room temperature. Curve A linearly increases, Curve B gradually decreases, and Curve C decreases sharply then remains constant. Identify the solutions for Curves A, B, and C respectively.

Professor PC Thomas Classes · Answer

Inorganic salts like KCl increase surface tension. Alcohols like $CH_3OH$ decrease it gradually. Surfactants like $CH_{3}(CH_{2})_{11}OSO_{3}^{-}Na^{+}$ decrease it sharply until the critical micelle concentration (CMC), then it remains constant.