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Dissolving iron in HCl, unknown product

  1. Apr 3, 2013 #1
    My class needed some iron (iii) chloride to determine the purity of some aspirin they synthesized, so I thought I might try making some. I left a strip of iron in concentrated HCl for a few nights under the fume hood. I was expecting a liquid with iron (ii) chloride to result, which would then gradually turn into iron (iii) chloride with time.

    What I got was a light greenish snow-like solid substance accumulating in the bottom of the beaker (regrettably did not get any pictures). I filtered this off, but now I am wondering exactly what it was. Nothing went into the beaker but the 9 g Fe strip and about 100 ml of 12 M HCl.

    The solution I ended up with performs like iron (iii) chloride, it will turn salicylic acid a purplish color. It is a very dark brown liquid that leaves yellowish trails on the sides of its container. I'm going to do a titration to get its exact concentration.

    I should've had a bunch of excess HCl since Fe was limiting the reaction. Could I have saturated the solution with iron (ii) chloride?
  2. jcsd
  3. Apr 3, 2013 #2


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    Staff: Mentor

    According to wiki solubility at room temp. is around 70g/100 mL, and you are below 20g/100 mL. Then, you have a huge excess of Cl-, so I wouldn't rule the precipitation out.

    How pure was the iron?
  4. Apr 3, 2013 #3
    It was a Flinn Scientific iron strip, which I believe are intended (or sold as) electrodes. I cut it up using snips. The package had been opened before, and some other pieces were showing very slight spots of rust. The one I cherry picked did not, though I did not look using magnification.

    Additionally, this billowing solid was noticeable long before the strip had completely dissolved.

    I will double check the packaging tomorrow morning, but I can't recall any quantitative indication of purity.
  5. Apr 17, 2013 #4
    Sounds like you got ferrous chloride (tetrahydrate) at the bottom.
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