Answer to Question #28522 in Organic Chemistry for Jody Solomon

Question

In a chemical reaction when a brightly colored shirt decomposes with repeated exposure to sunlight the color of the shirt fades. Is that an example of precipitation, acid base, gas evolution, or oxidation reduction and why?

Answer 1

Some outside component changes the chemical structure of the dye molecule. The action of sunlight can decolorize or bleach certain dyes, making them lighter. Because the dye has changed its chemical structure or composition this is a chemical change. UV light may cause the dye molecules to react or decompose (break up). Visible and ultraviolet light can interact with and break chemical bonds, not nuclear or subatomic bonds. Color is caused on the chemical or electron orbital level, not on the atomic nucleus level. Photons created at the atomic nucleus level are in the gamma ray energy levels.