Blue Bottle

The blue bottle experiment is a color-changing redox chemical reaction.

An aqueous solution containing glucose, sodium hydroxide, methylene blue is prepared in a closed bottle containing some air.

Upon standing, it spontaneously turns from blue to colorless. However, shaking the bottle causes the solution to rapidly turn blue again.

With further shaking, this color-change cycle can be repeated many times.

This experiment is a classic chemistry demonstration that can be used in laboratory courses as a general chemistry experiment to study chemical kinetics and reaction mechanism.

The reaction also works with other reducing agents besides glucose and other redox indicator dyes besides methylene blue.

Resource from: https://en.wikipedia.org/wiki/Blue_bottle_experiment