Description of experiment
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Needed compounds:
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acetyl acetone : CH3COCH2COCH3
cobalt sulfate : CoSO4.7H2O
ferric chloride : FeCl3 . 6H2O
hydrochloric acid : HCl
copper sulfate penta hydrate : CuSO4 . 5H2O
Class:
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elem=C,Fe,Co,Cu
coordination
Summary:
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Copper(II) ion and iron(III) ion form complexes with acetyl acetate (acac) in
aqueous solution. Cobalt does not form a complex, at least not visibly.
Description:
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Dissolve some ferric chloride in a 0.5% solution of hydrochloric acid: A clear
and yellow solution is obtained.
Add several drops of a saturated solution of acetyl acetone to this solotion:
The liquid becomes deep brown with a somewhat reddish/purple hue. The color is
very intense. The complex is stable. After one day of standing it still looks
the same. The liquid remains clear.
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Add a saturated solution of acetyl acetone in water to a solution of copper
sulfate: The liquid turns from light blue to a bright green color. The color
also is more intense than the color of the solution of copper sulfate. The
liquid remains clear.
Allow the liquid to stand for a few hours: Many small blue crystals have
settled at the bottom. The blue crystals are not glass-like, but are opaque.
Allow to stand for another day: Much more of the blue crystalline solid has
formed. The liquid above the crystalline solid still is green, but it has a
much lighter color (somewhat like a not too strong aqueous solution of
nickel(II)).
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Add a saturated solution of acetyl aceton in water to a solution of cobalt
sulfate in water: No visible change occurs.
Allow to stand for a day: Still nothing has changed. The solution is pink/rose
like a plain aqueous solution.