This post is not strictly science fair related, however, it is a really great demonstration of the effects of density and the fact that water is denser than ice. I found out about this experiment via a weekly email and have a few suggestions on helpful ways to change it. The original is here: Spangler's version . The run down is that you will use a layer of vegetable oil (density=0.91), a layer of mineral oil (density=0.8) and a piece of ice which will become water (densities = 0.91 and 1 respectively). Add a little food coloring in the bottom and you get some awesome magic!
So, here we go... Take a clear container and add a few drops of food coloring. Add the vegetable oil... only make it corn oil because it is slightly denser than vegetable oil (density=0.92). The food coloring will not mix with the oil because it is water soluable. Now add the mineral oil (baby oil works) by pouring it gently and slowly onto a spoon slanted to the surface. Make sure there is a good couple of inches of mineral oil on the top. Next comes the fun part... Grab an ice cube and place it gently on the surface and watch what happens.
Go... Do it... Then come back.
OK, (that was a pause so you could watch your setup) so what happens is that the ice floats between the two oils and then melts... Water (melted ice) is heavier than both the ice and the oil so it drips off and falls to the bottom where it mixes with the food coloring! Shazam!
Now, in my experiment, pictured below there is already a large layer of water in the bottom and the top of that layer looks a little dusty. The surface tension of the water layer at the bottom holds up the drips for a little while before they 'fall through' and mix with the water.
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