• Question: How does water purity affect surface tension?

    Asked by millerbei to Asif, Laura, Lena, Sean, Viv on 17 Mar 2012.
    • Photo: Lena Ciric

      Lena Ciric answered on 17 Mar 2012:

      I don’t really know about this but I’ve had a bit of a look for you. Apparently this depends on the nature of the impurities. If they are polar molecules, then they will lower the surface tension. If they are non-polar, then they will increase the surface tension.

      A polar molecule has poles with different electric charge. Water itself is polar and it therefore reacts with other polar molecules – this results in the lower surface tension.

    • Photo: Sean Murphy

      Sean Murphy answered on 18 Mar 2012:

      Yes, surface tension of water decrease on adding detergents like soap. Ask you teacher to do this experiment with the class:

Comments