Description of experiment
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Needed compounds:
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potassium iodide : KI
lead acetate : Pb(CH3COO)2 . 3H2O
Class:
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precipitate
Summary:
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Lead (II) forms a brightly colored precipitate with iodide ions.
This precipitate is soluble in water fairly well, when hot.
Description:
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Prepare a solution of lead acetate and add one drop of dilute acetic acid
(appr. 5% Ch3COOH) to this solution in order to make it clear. It is really
important to use distilled water for this solution.
To the solution of lead acetate add a solution of potassium iodide: A bright
yellow precipitate is formed immediately.
Heat the liquid until it is close to boiling: An appreciable amount of the
precipitate dissolves. The liquid becomes colorless. The yellow precipitate
dissolves as colorless compound in water.
Let liquid cool down slowly: Many small glittering crystals of lead iodide
are formed. These slowly settle at the bottom of the test tube.