# Science Trick: Blue Bottle

On shaking: it is BLUE!. . . . On standing it is COLORLESS! Here is why this happens…

WHY DOES THE COLOR CHANGE ??

What is in the solution?

• Sodium hydroxide – makes the solution basic
• Glucose acts as a reducing agent (loses electron)
• Methylene blue – acts as an indicator for the reaction

#### What is happening?

Glucose is a reducing agent and in basic solution will reduce methylene blue to a colourless form.

Shaking the solution admits oxygen which will re-oxidise the methylene blue back to the blue form.