Wednesday, March 4th, 2015
This blog post was written by Kelly Zhu, a junior at Whitney Young High School. She is one of the IIT Boeing Scholars, and with her STEM Ed(You)Cation team, is working on science outreach for family science nights.
Light reactions are one of many science experiments that are totally illuminating. It is a fun way to expose and engage children to science. The thionin reaction is an example of something that uses light as a reactant. This intensely purple solution changes color in the presence of white light. When the light is removed, it changes back to purple, so it is completely reversible!
Note: This reaction calls for things that really should be handled and stored in a lab. As a result, you couldn’t and shouldn’t try this at home.
Safety Note: As a safety precaution, be sure to wear goggles, gloves, and chemical resistant apron thought the experiment
Thionin is an organic compound that comes in two forms. When thionin is in its oxidized form it will be purple and when it is in its reduced form it will be colorless. A thionin reaction is basically converting light energy to chemical energy and vise versa with the help of light. In this demonstration, by adding a reducing agent such as iron(II) ion (Fe2+), the thionin molecule accepts two hydrogen atoms from iron and is reduced to its colorless form. However, this only happens when there is an intense light source to catalyze the reaction. Therefore, when the light source is removed, the thionin will return to its oxidized state and the purple color will reappear.
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