Chemistry Lecture Demonstrations - ChemPRIME

Chemistry Lecture Demonstrations

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"Chemistry" (?) of Vision

Use a photographic strobe to photolyze a Ferrioxalate Actinometer solution[1]. Ask if vision is a chemical process. It is when it's explained chemically [2].

Now demonstrate the "Moon Illusion" by creating an afterimage with a photgraphic strobe held at arm's length. "Balance" the afterimage on a finger held 30 cm from the eye, moving the finger from left to right, then move the finger closer to and farther from the eye. The image gets larger and smaller illustrating the Moon Illusion and "Emmert's Law": You see with you mind, not with your eyes". The "chemical image" on the retina remains the same size, of course. Perception (after image) is not a chemical process when understood in terms of mind or psychology.


  1. J. Chem. Educ., 1981, 58 (8), p 655
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