Surface Tension of n-Butanol Solutions Lab Report

After being amazed by the apparent “magic” of water’s high surface tension as children, most of us think little of the consequences of this interesting property of liquids. Surface tension plays a part in many common effects seen every day: a water stream breaking into droplets and the beading of water on a smooth, non-polar surface are just two examples.

In this lab, we became closely acquainted with the surface tension of an aqueous solution and what effects it had on surface concentration. We combined pure n-butanol with water in various concentrations to see how much effect it would have on the surface tension. Plotting the value of gamma (surface tension) in units of g/s2 for each of the concentrations presented a linear relationship. The slop of the line gave us what we needed to find the surface concentration using the Gibbs isotherm equation. Finally, we used this value to find an experimental molecular cross- sectional area which we compared to a theoretical one using computer-built molecular models.

Real-world applications of surface concentration and surface tension might be found in industries requiring precise control on fluid dynamics or homogenous distribution of solutes in solution. Molecular cross-sectional area has implications in molecular collisions and the energy found therein.

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