"Chemical traffic light" experiment
Сan a solution change its color by itself?
Can a liquid change colors by itself? Check out “Chemical traffic light” – a breathtakingly colorful reaction!
Wear protective gloves and eyewear when working with sodium hydroxide, as it causes burns upon contact with the eyes and skin.
Reagents and equipment:
- 40 mL 10% glucose solution;
- 25 mL 10% indigo carmine solution;
- 150 mL 1 M sodium hydroxide solution;
- 3 beakers.
Combine 150 mL 1 M sodium hydroxide solution, 40 mL 10% glucose solution, and 25 mL 10% indigo carmine solution in the flask. Watch as the solution gradually shifts from dark green to red, and then to yellow.
In an alkaline medium, blue indigo carmine turns green as it is oxidized by the oxygen in the air. Glucose then gradually reduces the indigo carmine, changing its color first to red, then to yellow. If the flask is shaken, the oxygen contained in the air oxidizes the indigo carmine, turning it back to green. The solution will continue to change colors until all of the glucose has been oxidized!