Water and oil do not form a solution that can be mixed. In most cases, you see ample amounts of water with a small surface layer of oil. However, in this reverse situation where droplets of coloured water have been placed in an oil solution, the results are depicted in the photo. The hydrophobic nature of the oil causes the coloured water to be repelled and to take on a spherical shape, since this provides the least surface area-to-volume ratio. Since the density of water is greater than oil, the drops sink to the bottom of the container. However, a few smaller water droplets remain at the surface due to the surface tension of the oil molecules. As more water droplets were added, the smaller droplets would become larger due to cohesion and would sink to the bottom.

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Matthew Kostanecki
St. Elizabeth Catholic High School, Richmond Hill, Ontario
Honourable Mention ( High School/CEGEP )

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