It's blue when shaken, but transparent when it stands ("Blue bottle" experiment)

A similar experiment is included in the MEL Chemistry subscription.
For MEL Science safe experiments subscription go here: https://goo.gl/gVFMND

Here’s an im­pres­sive mag­i­cal ex­per­i­ment with a bot­tle! You can con­duct this ex­per­i­ment at home with your friends!

Reagents and equip­ment:

bot­tle with stop­per;
10% sodi­um hy­drox­ide so­lu­tion;
methy­lene blue so­lu­tion;
glu­cose.

Step-by-step in­struc­tions

Place the glu­cose in the bot­tle, then add the sodi­um hy­drox­ide so­lu­tion, and then the methy­lene blue so­lu­tion. Mix to­geth­er, shak­ing the bot­tle. The so­lu­tion turns col­or­less. Shake the bot­tle again and the so­lu­tion turns blue.

Pro­cess­es de­scrip­tion

Methy­lene blue is an or­gan­ic dye and in­di­ca­tor which eas­i­ly re­duces to a col­or­less state. As a re­duc­er, glu­cose in an al­ka­line medi­um can be used. It re­duces methy­lene blue to a col­or­less form. If you shake the bot­tle, the oxy­gen con­tained in the air ox­i­dizes the col­or­less form back to a col­ored form. Then a re­verse trans­for­ma­tion to a col­or­less form takes place, un­til all of the glu­cose has ox­i­dized to glu­con­ic acid.

Safe­ty pre­cau­tions

Be care­ful when work­ing with di­lut­ed so­lu­tion of sodi­um hy­drox­ide. It is a cor­ro­sive sub­stance which can cause burns to the skin and mu­cous mem­branes.