Surface Tension of Aliphatic Alcohols

In a series of homologous compounds e.g. aliphatic alcohols, Traube noticed that for each additional CH2 group, the concentration to give a certain surface tension is reduced by a factor of 3. Langmuir gave an interpretation of this empirical rule by considering the work required to transfer 1 mol of solute from the solvent to the surface. 

Prepare stock solutions of the normal primary alcohols C H2n OH (n=3-5) in which the mole fraction, n, of the alcohol is 0.01. By successive dilution, prepare 4 or more solutions with decreasing mole fraction down to 0.001. Measure the suiface tension of each solution by a suitable method and plot it against log n. Using sec-or tert. butanol (butan-2 ol and 2-methyl-propan-2 ol) prepare solutions similar to those used above and carry out similar runs and comment on your results. 

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