These photographs depict the molecular diffusion of blue food dye in a glass of water over a time period of 2 minutes. The food dye then took the role of the higher concentrated fluid, while the water was the fluid with the lower concentration. As can be seen, the higher concentrated fluid gradually spread out over the whole water, mixing until the water becomes a solid greenish colour. When the water reaches that point, the two fluids have reached equilibrium. Yet total equilibrium can only be reached if there is no net force acting on the particles. These pictures show one external force: gravity. This is why most of the dye first sinks to the bottom and then resumes diffusing from there.

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Tia Ishii
John Abbott College, Ste. Anne de Bellevue, QC
Honourable Mention ( High School Individual Category )

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