School of Physics Lecture Demonstration Manual

Fb-10 Surface Tension of Aqueous Solutions

Published: Friday 10 March 2006 - Updated: Tuesday 29 March 2011

Aim

To demonstrate that in general organic substances dissolved in water lower the surface tension.

Apparatus

Diagrams

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Surf Ten of Aqu Solutions Diagram

Description

If a piece of camphor is scraped into a dish full of water it will dart over the surface in a seemingly random manner.

Camphor is only slightly soluble in water. On an uneven piece of camphor, solution occurs more rapidly at a point P than where the surface is smooth. The strength of the camphor-water solution near P is greater than at any other point and hence the surface tension is least at P. THerefore the greater tensions on the other side pull the camphor away from P.

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