Iodine clock experiment is a classical chemical clock demonstration. it was discovered by Hans Heinrich Landolt in 1886. It is a great magic trick to impress children on a birthday party. Two colourless solutions are mixed and at first there is no visible reaction. But the impressive effect comes after a short time delay, when the liquid suddenly turns from transparent to dark blue. The iodine clock reaction exists in several variations. In some examples you can the dark colour is more blue and in some cases we get it completely black.
Iodine Clock Experiment Explanation
The iodine clock reaction times how long it takes for a fixed amount of thiosulphate ions to be used up, i.e. the time taken for the iodide ions to reach a fixed number of moles produced in the reaction between potassium iodide and an oxidising agent (usually hydrogen peroxide, or sodium peroxodisulphate).
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