Chemically there are also traffic lights, and of course more magical than the traffic lights on the road. Xiaobian brings you to the following:
Experimental principle: The solution in the bottle contains three components: sodium hydroxide, D-glucose and indigo carmine (or acid indigo). Indigo Carmine is a redox indicator, and at the same time it has the role of an acid-base indicator (similar to the effect of potassium permanganate in titration), that is, under the action of redox reaction and pH. It can change a variety of colors. Indigo Carmine has three different redox states. In this reaction system, when the bottle is shaken, it is oxidized by oxygen in the air, and is again reduced by glucose upon standing, thereby causing discoloration. If the reaction is carried out in a different pH environment, the color will change. The following figure summarizes the specific color change status:
In addition, indigo carmine red has other uses besides being used as an indicator. It is a food coloring (E132) that is also used in some urinary system procedures. In terms of the safety of the experiment, sodium hydroxide plays a role in pH adjustment in this experiment, and does not use a very concentrated solution, so it is safer, and glucose and indigo carmine are not dangerous themselves. Conditional friends can also do their own work and make cool experimental results in the lab.
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