Blue bottle experiment
The blue bottle experiment is a classic chemical show experiment . In a closed vessel there is a colorless liquid and some air. If you shake the vessel, the liquid turns blue. However, after a short time the color disappears again. The longer you shake, the longer the color stays.
From a chemical point of view, this experiment can also be used as a model experiment for a redox system related to NAD + / NADH 2 . In addition, the shaking time is proportional to the staining time ( 1st order reaction ).
reaction
The discoloration reaction is based on the reduction of a methylene blue solution to the leuco form by glucose , which is oxidized to gluconic acid.
When shaken, the leuco-methylene blue is oxidized again to colored methylene blue by oxygen from the air. The more intensely you shake, the longer the coloration lasts. If there is a sufficient excess of glucose, this experiment can be repeated until the atmospheric oxygen in the sealed test vessel is completely reduced.
Web links
- Description on Chemieunterricht.de , accessed on November 15, 2017.
- Test instructions from the University of Würzburg , accessed on November 15, 2017.
- Video: Experiment of the week: What is the "Blue Bottle"? . Leibniz Universität Hannover 2011, made available by the Technical Information Library (TIB), doi : 10.5446 / 2095 .