In this video, I'll be demonstrating how anyone can make their own iodine clock reaction with simple over-the-counter chemicals.



Household Materials Needed:

.Hydrochloric acid (for cleaning purposes)

.Hydrogen peroxide (3%)

.Sodium hydroxide (drain cleaner)

.Povidone-iodine (antiseptic)

.Cornstarch

.Sodium thiosulphate (used as water conditioner for fish bowls, but I got mine from a children's chemistry game)



The Reactions

In the first, slow reaction seen in the video above, triiodide ion is produced:



H2O2 + 3 I- + 2 H+ -> I3- + 2 H2O



In the second, fast reaction, triiodide is reconverted to iodide by the thiosulfate:



I3- + 2 S2O32- -> 3 I- + S4O62-



The color of the solution after the reaction is a result of the complex formed between iodine and starch that has dark blue color.