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)
- 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.
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