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Drying Out Iron Chloride

  1. Jun 25, 2005 #1


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    I have/had a solution of Iron (III) Chloride. I wanted to extract the Iron Chloride out of solution, so I decided to evaporate all the water off and just collect the crystals that form, right? Wrong, appearently, it is very hygroscopic making it some what difficult to actually dry it. I have gotten it to a thick, dark brown, "muddy" lucking substance, but it wont dry any further. I am attempting to evaportate off the water in the hot summer sun, but after about a week at this same stage, it hasnt changed.

    Is there another way of de-hydrating, this substance that seems to just love water?

    I cant really heat it very much (using an oven or flame) because, for one, I have it in a plastic container because Iron Chloride acts like an acid on metals, so I dont want to melt the container, and two, I think that the Iron Chloride melts and deomposes at a very low temperature, so I dont want to alter the substance either.

    I suppose, in theory, if I could put it in a container that is air tight, the lower the pressure sugnificantly, I could lower the boiling point of water and pump the steam out. But this is a little to much in the way of building something than I had intended. Is there an easy chemical way?
    Once I get it dried out, all I need to do is make sure I keep it in a sealed container, so as not to let any more water get to it.
  2. jcsd
  3. Jun 27, 2005 #2
    It will decompose to a basic iron chloride, or even ferric hydroxide. It's tough to get ride of the water with just heating.

    I'm not sure if pulling a vacuum on it will do the job either, worth a try I suppose.

    Normally anhydrous ferric chloride is made by passing chlorine over hot iron, the FeCl3 drops out of the vapour state downstream as the gases cool.

    You can heat it in a stream of HCl gas, or mix it with several times its volume of ammonium chloride and then heat the mixture to drive off water and excess NH4Cl. The ammonium chloride functions as a local source of HCl.

    You _might_ be able to do it by using azotropic distallation. Drop the FeCl3 into some alcohol, ethanol or isopropanol will do, and add some heptane or toluene. Then slowly distill off the water-alcohol-hydrocarbon azeotrope, the alcohol replacing the water as a complexing agent with the FeCl3. Once all the water is removed, the alcohol and hydrocarbon can be distilled off until the FeCl3 starts to crystallize out. Again, I can't 100% promise that will work.

    One more route would be to add more HCl and then extract the FeCl3 from the water using ether, and remove the organic solvent.

    All of those mean using glassware, plastic isn't going to cut it.

    Hmm, also see:
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