Iodine Clock

Iodine Clock

Credit: CCAlive!
 
Author: Claire Liu
Description:

Most chemical changes involves color changes. The demo, "Iodine clock", is a classic color-changing reaction.

A solution of hydrogen peroxide and sulfuric acid is added to a solution of iodide ion, thiosulfate ion, and starch. A slow reaction forms triiodide, which reacts rapidly with thiosulfate, until the thiosulfate is consumed. The excess triiodide then reacts with the starch to form a blue complex.
Usage:
No Description available
 
Futher Images
tn_iodine-clock-to-obs-13-p1-120.jpg tn_iodine-clock-to-obs-13-p2-120.jpg tn_iodine-clock-to-obs-13-p3-120.jpg tn_iodine-clock-to-obs-13-p4-120.jpg  
Credits, from left: CCAlive!, CCAlive!, CCAlive!, CCAlive!
 
Safety:

Wear goggles and gloves.
 
Equipment:

Small beaker or glass bottle;
 
Materials:

hydrogen peroxide and sulfuric acid solution;

iodide ion, thiosulfate ion, and starch solution;
 
Procedure:

First put some of the solution of iodide ion, thiosulfate ion, and starch in a small beaker or glass bottle and then add the solution of hydrogen peroxide and sulfuric acid.
 
Notes:
No Description available
 
Disposal:
No Description available
 
Difficulty:Some laboratory experience required
Preparation Time:  minutes Demonstration Time: 1 minutes
Availability of Materials:Not specified Cost of materials:$ 
Last Updated:Tue 21 Jun 2011 12:49:01 EDT Viewed:67173 times viewed
Source:University of Wisconsin press, Shakhashiri; UW-madison chemistry department; JCE CC Alive!, Shakhashiri, B.Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry