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Topic: Problem with the solution of a copper complex lab  (Read 17611 times)

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duderanch

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Problem with the solution of a copper complex lab
« on: October 06, 2005, 01:26:15 AM »
Ok, so I've done a very long lab where you have to determine the a formula of a copper complex through titrations and such (common lab i think) and got my answer which I think is correct. The problem is that it doesnt balance out correctly.
 Its

CuSO4*5H20 + XNH4 results in CuSO4(NH4)x(H20)

My problem is with the H20. I got 1 mol H20 is in the final product. But clearly for the equation to be balanced it would have to be 5 moles. I don't think thats right because it isnt much of a reaction then (you're just adding x number of NH4 moles) and my moles h20 are nowhere near 5. I was thinking that another product is just plain old H20 and i would end up with 4 moles of that. But it doesnt state that as a product in my lab book which makes me skeptical about it. Anyboy know much about this lab to provide insight?

Offline AWK

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Re:Problem with the solution of a copper complex lab
« Reply #1 on: October 06, 2005, 03:31:41 AM »
Ammonia is NH3 or NH3(aq) or NH3.H2O (or NH4OH) but not NH4 !
CuSO4.5H2O + 4NH3(aq) = [Cu(NH3)4]SO4(aq)
You do not need counting water molecules in water solution.

If you did experiment with pulverised copper sulfate hydrate and gaseous ammonia, some water is removed with an excess of ammonia and then reaction l ooks like:
CuSO4.5H2O + 4NH3 = [Cu(NH3)4]SO4 + 5H2O
or
CuSO4.5H2O + 4NH3 = [Cu(NH3)4]SO4.H2O + 4H2O
if you got crystals of defined hydrate of  copper complex.
AWK

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