hodges
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Registered: 17-12-2003
Location: Midwest
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Ferric Ammonium Citrate + Calcium Chloride Gives No Precipitate
I dissolved 1g of ferric ammonium citrate in a small amount of water (few ml).
Likewise, I dissolved 1g of calcium chloride in a small amount of water (few ml).
I mixed the two. Since both calcium and citrate ions are present, and the solubility of calcium citrate is less than one gram per 100ml of water, I
would have expected to see a precipitate of calcium citrate. But no precipitate, and no visible changes at all. Why?
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DraconicAcid
International Hazard
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Location: The tiniest college campus ever....
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Mood: Semi-victorious.
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Because the citrate is coordinated to the iron(III) ions and won't let go. If you add sodium hydroxide, you will also not see any iron(III) hydroxide
forming.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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hodges
National Hazard
Posts: 525
Registered: 17-12-2003
Location: Midwest
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I tried adding NaOH solution to the mixture. At first, I get a gray precipitate. This might be the calcium citrate I was looking for, but it might
also be a mixture of iron and calcium hydroxides. As I continue to add more NaOH, the precipitate becomes brown, and appears to be iron(III)
hydroxide.
Also tried adding NaOH solution to just the ferric ammonium citrate. I get a brown precipitate only, likely iron (III) hydroxide, and I do smell
ammonia.
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