Introduction: How to Make an Iodine Clock Reaction at Home

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)
.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.