jamit
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copper II chloride anhydrous
does anyone know how to make copper II chloride anhydrous from copper II chloride dihydrate? Heating it would only decompose it and produce CuO and
toxic HCI.
I checked goggle but found nothing conclusive. Someone suggested adding a few drops of conc. HCI to copper II chloride dihydrate and heating gently
to prevent hydrolysis. Has anyone tried this? Any help would be appreciated. thanks in advance.
[Edited on 10-2-2011 by jamit]
[Edited on 10-2-2011 by jamit]
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a_bab
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In order to prepare CuCl2 anh. you need 3 steps.
The first step gets rid of the main part of the water; it consists in heating gently the chloride till the hydrated chloride liquifies and water
starts to boil off. The resulting porous mass is further dehydrated in the step 2, where it is heated to some 400 degrees in a constant gaseous HCl
stream. This will avoid the decomposition reaction you mentioned.
The third step means heating the chloride placed in a boat, all in a closed tube, in a dry HCl atmosfere up to 500 degrees C. It must not melt,
otherwise it's hard to remove from the boat.
While on this, you may want to sublimate it, rendering trully anhydrous CuCl.
It is kept sealed in a glass tube.
Same method applies to chlorides of Zn and Mn, with different temperature ranges/heating times.
Not the kind of experiment you'd want at home as you can see unless you have a good hood and a good supply of choking dry gaseous HCl.
Good luck.
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Retard-3000
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anhydrous copper(II) chloride can be made easily by simply heating the dihydrate above 100C, it will not decompose at all until it reaches
temperatures around 993C.
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woelen
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I agree with Retard-3000. If you have the pure hydrated salt (cyan green color, not green like grass), then simply (but carefully) heating the
crystalline solid in a clean glass beaker allows formation of the anhydrous salt. The color of the resulting product depends on the size of the
crystals from which you start. With crystals of mm size, you obtain a chocolate brown solid. If you start from very fine crystals or powder you obtain
a mustard-colored powder. The chocolate brown solid also can be ground to a mustard yellow/brown powder.
I tested the anhydrous salt by adding this to water. It gives a clear green solution, which only shows faint opalescence. So, probably a tiny fraction
of the chloride is lost as HCl, but I bet it is at most in the order of tenths of percents, otherwise a solution of the resulting product would be
really turbid and not only slightly opalescent.
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a_bab
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That method is for getting really anhydrous CuCl2, without traces of water. Got it from a russian book with very exciting synths, such as tens of Pt
compounds, W bronze, metals distillations (alkali - alkali earth along with their chemical isolations) etc. All lab procedures.
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jamit
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Thanks Retard-3000 and Woelen, I'll try your method of slowly and carefully heating it this weekend.
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