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Author Topic: I need a HARD salt! Any suggestions?  (Read 1790 times)

Offline ewh

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I need a HARD salt! Any suggestions?
« on: 19/01/2015 20:32:56 »
Hi everyone!

I need a non toxic easily water soluble substance with VERY hard crystals.

I have some marble mortars and pestles contamianted with non water soluble salts. (Maybe only one; CuCO3•Cu(OH)2)
An easy metod to remove residue, without destroying the mortar, is to grind something else in there. The old residue will the be mixed up in that "something" and leave with the rest when you empty the mortar, but the "something" needs to be water soluble. Otherwise IŽll only swap one contamination for another.
I also need to be able to throw this in the sink with a good conscience.

Any suggestions?
..preferably something cheap and easy to buy or make yourself.

Thanks in advance  / Erik


 

Offline chiralSPO

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Re: I need a HARD salt! Any suggestions?
« Reply #1 on: 19/01/2015 20:48:28 »
I can see why you wouldn't want to wash your mortar with acid, but I think aqueous ammonia should dissolve copper carbonate (it definitely dissolves Cu(OH)2 and CuO), without reacting with calcium carbonate (marble) or agate.

But if a safe, hard, water soluble salt is what you're really after, I would recommend NaHCO3 or Na3PO4. Unfortunately the really hard salts are also typically insoluble in water (presumably the lattice energy prevents both mechanical breakage and dissolution...)

EDIT: I just looked it up, and malachite is definitely soluble in ammonia. Also a nice bonus with this method is that the copper-ammonia complex is water soluble and very strongly colored, making it both beautiful and easier to see than the starting impurity (even if the mortar looks clean, do another rinse with ammonia--if it turns blue, keep going until it doesn't)
« Last Edit: 19/01/2015 21:17:30 by chiralSPO »
 

Offline CliffordK

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Re: I need a HARD salt! Any suggestions?
« Reply #2 on: 20/01/2015 00:02:27 »
What about basic salt?  NaCl or KCl.
 

Offline ewh

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Re: I need a HARD salt! Any suggestions?
« Reply #3 on: 20/01/2015 11:03:07 »
Thank you!
Where did you find the information about hardness, chiralSPO and CliffordK?
 

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Re: I need a HARD salt! Any suggestions?
« Reply #3 on: 20/01/2015 11:03:07 »

 

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