Question

How do I test for the contamination of water with iodide ions?

Answer 1

Make solutions of `Pb(NO_3)_2(aq)` and `NaI(aq)`

Explanation:

`Pb^(2+) + 2I^(-) rarr PbI_2(s)darr`

Lead iodide is very insoluble, and precipitates from aqueous solution as a canary yellow solid. So treat the water from the pipe with `Pb(NO_3)_2(aq)` to see if precipitation occurs.

I propose that you test the reaction by mixing `Pb(NO_3)_2(aq)` with `NaI(aq)` so that the results of a positive test can be appreciated.

And now test the water from the pipes with sodium iodide in a separate reaction.