Demonstration of the iodine clock experiment

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

  1. 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!

  2. Hi Stephen
    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 ( 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!

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