Traffic Light Experiment

Session focus: Reversible Redox Reactions!

https://video.wixstatic.com/video/740470_4187164032aa40aca4fa1125b4333d67/1080p/mp4/file.mp4

Today, we introduced our younger secondary students to the concept of redox reactions using the traffic light experiment as a fun analog!

In this experiment, we used a mixture of glucose, indigo carmine, and sodium hydroxide to replicate the three colors of a traffic light: red, yellow, and green. We demonstrated how the interaction of these substances, plus oxygen, resulted in a sequential colour change.

• Reduced State (Yellow):

• When left to stand, no oxygen is mixed in and the glucose is left to reduce the indocarmine, turning the solution yellow. 

• Partially Oxidized State (Red):

• When shaken, oxygen is mixed and the solution is slightly oxidised, turning red.

• Fully Oxidized State (Green):

• When shaken roughly, more oxygen is mixed in and the solution is fully oxidised, turning green.

https://video.wixstatic.com/video/740470_4e039ee7e2da4357ad1a5ef55e1a3da8/1080p/mp4/file.mp4

Lesson Materials

• Glucose

• Distilled water

• Sodium Hydroxide

• Indigo carmine indicator

• Conical Flasks

• Spatula

• Beakers

Lesson Plan:

1. Let the students prepare the following solutions: Solution A:   6g glucose + 200ml distilled water + 40ml Sodium Hydroxide Solution B:   Indigo carmine + 125ml distilled water
   

2. Pour the alkaline solution of glucose (Solution A) into the indigo carmine solution (Solution B) and observe change in colour

3. Let the solution stand for 5 minutes

4. Shake the solution to reverse the reaction (oxidise the solution)!