Measurement of the surface tension of water detergent solution: An informative study for the general public

Abstract

We performed an experiment to test the ability of various commercially available detergents to lower the surface tension of water. Powdered detergent of known mass is dissolved in tap water and the corresponding change in the surface tension was recorded. Determination of the surface tension employed the Du Nouy ring method. A strain gauge (custom made using variable resistors) interfaced to a computer via a data acquisition card (DAQ, LabView) was used to measure the surface tension force. This enables us to obtain as many trials as possible with only little processing time, thereby making our results more accurate and reliable. Results show no significant difference among the sampled detergents in lowering the surface tension.