This experiment demonstrates the iodine clock reaction between iodide and persulfate ions, using thiosulfate as the ‘clock’. After some introduction details, three experiments are performed: studying the effect of concentration to determine the orders of reactants (3:01), studying the effect of temperature to determine the activation energy (7:47) and studying the effect of solvent polarity (9:42).
Funding from NDLR and DIT gratefully acknowledged.
3 thoughts on “Demonstration of the iodine clock experiment”
Michael this is a very nice production indeed. I do a similar practical with my year one students; it works well and demonstrates rate of reaction nicely. Thanks for making this available!
Thanks a million. I enjoyed making it – it was interesting to think about the bits you need to shoot to make a video (maybe I should have got advice from your Chemtube students!). I have just reproduced it to zoom in a bit and get rid of the black bars either side. Also, i have packaged the video in an Articulate resource (http://bit.ly/hM2kTf) which has a quiz at the end – to be used as a pre-practical. Looking forward to using it, glad to hear that it works well with you – that gives me hope!!
Thanks again, hope this is the first of many!
Addendum: Nice new paper in J Chem Ed on microscale iodine clock (using peroxide):
A Microscale Approach to Chemical Kinetics in the General Chemistry Laboratory: The Potassium
Iodide Hydrogen Peroxide Iodine-Clock Reaction: http://pubs.acs.org/doi/abs/10.1021/ed100140w
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