Iodine clock reaction Chemistry Experiment

I’m going to add the chemical solutions into 2 cups which I marked A & B. both cups I already pour 40 ml of distilled water, then in cup A I add (2) small scoops of Sodium Iodate.

 

This experiment comes in a kit with the details where to buy it in the description below.

 

Now for cup B add (1) scoop of sodium sulfite and (4) scoops of Citric acid. Then add 8 drops of Starch solution. Stir both cups very good until it all dissolves.

 

Now to make the magic happen. I’m going to Pour both clear solutions from cup A and B into a empty 3rd cup and wait about 10-15 seconds.

 
TADA!

How it works!
Iodine has two different “oxidation states” – one where the iodine molecules have a negative charge (I-) and the other where they have no electric charge (I0) Only the iodine with no electric charge can combine with starch to make the blue-black color.

 

Certain chemical reactions (called oxidation and reduction reactions) can make iodine shift back and forth between these two states…

 

When Solutions A and B are first mixed, all the iodine has a negative charge, and two separate reactions begin. Reaction #1 (oxidation) changes all of the negative charge (I-) to no electric charge (I0), but Reaction #2 (reduction) is faster and changes the I0 right back to I- again, so it has no chance to combine with the starch. The iodine zooms back and forth between these two states thousands of times a second (of course you can’t see this) until all of a sudden the chemicals that make Reaction #2 happen are all used up. Then it’s time for Reaction #1 to change all of the I- to I0 one last time, it combines with the starch, and – you have “INK!”

 

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