Iodine reaction in water?

[yuzu]

I dipped a coral in a mixture of Lugols iodine and tank water last night and it was tea coloured then. I left the mixture overnight and now it is a very pale, almost colourless liquid. Has the iodine been converted into something else?

 

[Randy Holmes-Farley]

Yes, the I2 in Lugols is quite reactive. It reacts with organics and possibly other constituents such as bromide. I2 is colored and those other products are not.

The chemical reduction of molecular iodine in seawater

Molecular iodine is shown to be unstable in seawater. Eighty-five per cent of 1400 μg l−1 of I2-iodine added to an inshore seawater was chemically red…

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