Question

Salts that are insoluble in water are made by precipitation.
● Lead(II) iodide, PbI2, is insoluble in water.
● All nitrates are soluble in water.
● All sodium salts are soluble in water.
You are provided with solid lead(II) nitrate, Pb(NO3)2, and solid sodium iodide, NaI.
Describe how you would make a pure sample of lead(II) iodide by precipitation.
Your answer should include:
● practical details
● a chemical equation for the precipitation reaction.

Answer 1

Dissolve some of the solid NaI in one beaker containing distilled water. Dissolve some of the solid Pb(NO3)2 in another beaker containing distilled water. Pour the contents of one beaker into the other beaker. Stir and allow to stand for a minute or two. Set up a filter apparatus. Pour the contents of the mixture. Wash the remaining precipitate from the beaker with distilled water, then wash the ppt in the filter paper with several portions of distilled water. Allow the contents of the filter paper to air dry. That will be solid PbI2.
Pb(NO3)2(aq) + 2NaI(aq) ==> PbI2(s) + 2NaNO3(aq)