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

Nov 7, 2016

Make solutions of $P b {\left(N {O}_{3}\right)}_{2} \left(a q\right)$ and $N a I \left(a q\right)$

#### Explanation:

$P {b}^{2 +} + 2 {I}^{-} \rightarrow P b {I}_{2} \left(s\right) \downarrow$

Lead iodide is very insoluble, and precipitates from aqueous solution as a canary yellow solid. So treat the water from the pipe with $P b {\left(N {O}_{3}\right)}_{2} \left(a q\right)$ to see if precipitation occurs.

I propose that you test the reaction by mixing $P b {\left(N {O}_{3}\right)}_{2} \left(a q\right)$ with $N a I \left(a q\right)$ 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.