Water Properties

Surface Tension on a Penny


Recently we did a lab about the properties of water.  What we did was take water and used it in it's different forms and structures. The one that I found most interesting is the lab with the penny.  How did that little penny hold so many drops!!!  After I watched he video about the water properties I found that a little penny like that can hold so many drops by surface tension.  Surface Tension means the energy needed to increase the surface area of a liquid by a given amount.  In this case it means that the surface area expands the surface area so that it makes a spherical form.  So when you put the drops on the penny it makes a bubble like structure on top of the penny.

Second we took a string and water and put another glass at the other end and poured the water down the string. I thought it was crazy how it just stuck the string and ran down into the glass.  So I went to the video again and I couldn't figure out what property it was but then as I watched it over and over again I found it similar to cohesion.  Cohesion means an attractive force between similar molecules in the same phase.  See on the video it uses water going up a tree to get water to its leaves as an example.  Well this is the same thing its just that it is running down the string instead of up the roots.  Cohesion allowed the water to stick to the string and run down into the glass.