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Malachite and HCL Reactoin

Posted by RayOfOz  
RayOfOz January 31, 2006 03:17PM
I am doing an example in class in which we powder malachite and add to it 5% HCL, then add an iron object to extract the copper (field test for malachite). I was wondering if anyone could complete/correct this formula reaction for me. I'm not all that great at chemical equations.

Cu2(CO3)2(OH)2 + HCL CO2 + H2O + Cu2CL ???

Any help would be greatly appreciated.
Dr. Peter Haas February 01, 2006 09:15AM
Your malachite formula is wrong. The overall reaction is:

Cu2(CO3)(OH)2 + 4 HCl -> CO2 + 3 H2O + 2 CuCl2
Rayofoz February 02, 2006 02:29PM

The formula for Malachite I took directly from Simon and Schuster's Guide to Rocks and Minerals. I was able to find a complete formula showing the reaction of iron with the cloride ions.

2Fe +Cu2CO3(OH)2 +4 HCL - CO2(g) + 3H2O(aq) + 2FeCl2(aq) + 2Cu(s)
Al Konyers March 08, 2006 01:59PM
hi I'm not very good at chemistry and could need some help.

what is the structural formula of malachite?
Are the atoms all connected like in HCl or are they ionic, like NaCl?
David Von Bargen March 08, 2006 02:20PM
The carbonate and hydroxl anions will tend to stay together when malachite is dissolved (and are in that state in the solutions from which malachite grows).
Al Konyers March 08, 2006 02:36PM
Thanks, so if I got you right, the structural formula of malachite would look like this?

David Von Bargen March 08, 2006 02:55PM
No, actually the structural formula is Cu2(CO3)(OH)2.
A simplified formula would be Cu2CH2O5. The partitioning of the oxygen in the carbonate and hydroxl groups connotates the structural grouping of the anion elements. (the carbonate is actually the carbon surrounded by three oxygens, and doesn't have O-O bonding).

The exact positions of the atoms in the unit cell can be found by searching for malachite at:
Manas Das August 22, 2006 07:13AM
We came to know that considerable amount of dolomite in malachite consume more acid. Therefore, material is rejected for procesing. How do measure dolomitic Index that indicate the dolomite quantity ?
Pls. Help. I need your support
Paul L. Boyer August 24, 2006 02:40AM
My copy of Simon & Schuster's has the formula, Cu2(CO3)(OH)2, given by the esteemed Dr. Haas. Since azurite, Cu3(CO3)2(OH)2 is listed right beside malachite, I wonder if your mind combined the two formulae. Heaven knows my mind has messed with me that way.
kurt li March 06, 2013 12:07PM
But what are the observable reactions?
Alfredo Petrov March 21, 2013 01:05AM
First fizzing, as carbon dioxide is released as bubbles. Then the acid changes from colourless to green-blue as Cu ions go into solution.
Doug Daniels March 21, 2013 05:20AM
Then, if you add a piece of iron, it changes from gray to copper colored, and (ideally) the solution color changes from blue to....greenish (depends on acidity, whether the Fe+2 oxidizes, whether you paid your taxes on time,.....)
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