<Tr> <Td> (MB) (adsorbed on clay) </Td> <Td> 596 </Td> <Td> 80000 </Td> </Tr> <Tr> <Td> (MB) (adsorbed on clay) </Td> <Td> 570 </Td> <Td> 114000 </Td> </Tr> <P> Methylene blue is widely used as a redox indicator in analytical chemistry . Solutions of this substance are blue when in an oxidizing environment, but will turn colorless if exposed to a reducing agent . The redox properties can be seen in a classical demonstration of chemical kinetics in general chemistry, the "blue bottle" experiment . Typically, a solution is made of glucose (dextrose), methylene blue, and sodium hydroxide . Upon shaking the bottle, oxygen oxidizes methylene blue, and the solution turns blue . The dextrose will gradually reduce the methylene blue to its colorless, reduced form . Hence, when the dissolved dextrose is entirely consumed, the solution will turn blue again . The redox midpoint potential E' is + 0.011 mV . </P> <P> Methylene blue is also a photosensitizer used to create singlet oxygen when exposed to both oxygen and light . It is used in this regard to make organic peroxides by a Diels - Alder reaction which is spin forbidden with normal atmospheric triplet oxygen . </P>

What color is methylene blue in the reduced state