Iodine Clock Experiment

Set up five flasks of the iodine clock experiment. Everyone was assigned to collect the same amount of each reagent and the experiment was designed to look at how if different people make simple little mistakes or errors in their measurement of the samples, it can affect an overall reaction.

The following is courtesy of http://en.wikipedia.org/wiki/Iodine_clock_reaction

This reaction starts from a solution of hydrogen peroxide with sulfuric acid. To this is added a solution containing potassium iodide, sodium thiosulfate, and starch. There are two reactions occurring in the solution. In the first, slow reaction, the triiodide ion is produced . H2O2(aq) + 3 I-(aq) + 2 H+ → I3- + 2 H2O. In the second, fast reaction, triiodide is reconverted to iodide by the thiosulfate. I3-(aq) + 2 S2O32-(aq) → 3 I-(aq) + S4O62-(aq)

After some time the solution always changes color to a very dark blue, almost black.

When the solutions are mixed, the second reaction causes the triiodide ion to be consumed much faster than it is generated, and only a small amount of triiodide is present in the dynamic equilibrium. Once the thiosulfate ion has been exhausted, this reaction stops and the blue color caused by the triiodide - starch complex appears.

Anything that accelerates the first reaction will shorten the time until the solution changes color. Decreasing the pH (increasing H+ concentration), or increasing the concentration of iodide or hydrogen peroxide will shorten the time. Adding more thiosulfate will have the opposite effect; it will take longer for the blue color to appear.

Category:

Education

Tags:

• iodine
• clock
• experiment
• hydrogen
• peroxide
• iodide
• blue
• black
• starch
• chemistry
• science
• unlimited
• time

[xXBL1T2Xx]

lol i had to look this up for homework xD

[corvetlover1]

cool im goin to do this experiment

[melissaram1106]

Hello, if you don't mind me asking - what liquids did you use?