Question

The scenario: The time is well into a zombie apocalypse, the internet is no longer a thing, and all the vitamin shops have been scavenged. How can one obtain Potassium Iodide? Is it possible to extract it from plants?

Or is there a way to get from Potassium Hydroxide to Potassium Iodide? Without using iodine, because the purpose in this is to make iodine

Answer 1

You can extract iodide from seaweed.

Explanation:

Ribbon seaweed are rich in iodine which can be extracted.

The seaweed is heated to an ash where the iodine is present as iodide ions `sf(I^-)`.

The iodide is water soluble so the ash is treated with boiling water to extract the iodide.

I you wish, this can then be converted to iodine. After filtration, the iodide is converted to iodine by treating with a suitable oxidising agent such as hydrogen peroxide in acid conditions:

`sf(H_2O_(2(aq))+2H_((aq))^(+)+ 2I_((aq))^(-)rarrI_(2(aq))+2H_2O_((l)))`

A suitable solvent such as cyclohexane is added into which a lot of the iodine dissolves to give the characteristic purple colour of molecular iodine in the top layer:

The bottom layer is run off and discarded. The top layer is run into an evaporating dish and allowed to crystallise to leave solid iodine.

Full practical details and risk assessments can be found here, courtesy of The Royal Society of Chemistry:

http://www.rsc.org/learn-chemistry/resource/res00001915/extracting-iodine-from-seaweed?cmpid=CMP00006633