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Topic: How does Copper(II) nitrate react with Ammonia?  (Read 34369 times)

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Offline kingkurry

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How does Copper(II) nitrate react with Ammonia?
« on: November 02, 2010, 10:18:01 PM »
I need to figure what reaction will occour when Ammonia is poured into a copper(II) nitrate solution. Yes, there is water present. Here is the equation i got, but i feel like i am wrong:  3Cu(NO3)2 + 4NH3OH -->  2Cu(OH)2 + Cu(NH3)4 + 3NO3

I think there is OH because the Ammonia is a base and by defenition would increase the concentration of OH- ions and the copper would naturally bond to these, but im not 100 % sure.

Also is it the  Cu(NH3)4 that makes the dark blue color, or is atleast a darker blue than Cu(NO3)2?

Also what exactly is Cu(NH3)4 called?

Offline AWK

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Re: How does Copper(II) nitrate react with Ammonia?
« Reply #1 on: November 03, 2010, 06:09:56 AM »
[Cu(H2O)4]2+ + 4NH3 = [Cu(NH3)4]2+ + 4H2O
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Offline Schrödinger

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Re: How does Copper(II) nitrate react with Ammonia?
« Reply #2 on: November 03, 2010, 08:33:56 AM »
@AWK : What about the nitrate part? The question does state the presence of nitrate group... So my guess is :

5Cu(NO3)2 + 8NH4OH = 2Cu(OH)2 + 2[Cu(NH3)4](NO3)2
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Offline rabolisk

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Re: How does Copper(II) nitrate react with Ammonia?
« Reply #3 on: November 03, 2010, 10:11:11 AM »
The nitrates are spectator ions.

Offline AWK

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Re: How does Copper(II) nitrate react with Ammonia?
« Reply #4 on: November 03, 2010, 12:25:14 PM »
@AWK : What about the nitrate part? The question does state the presence of nitrate group... So my guess is :

5Cu(NO3)2 + 8NH4OH = 2Cu(OH)2 + 2[Cu(NH3)4](NO3)2

Ammonia is the limiting reagents in the complexation reaction. You can expect complex ions with 1-4 ammonia molecules. Only when molar ratio of ammonia:Cu2+ is 2 or slightly greater you can observe nearly quantitative precipitation of Cu(OH)2. Of course, at the some stoichiometries some basic salts can be formed, but I do not know if the copper basic nitrates are poorly soluble (I know for example Cu(OH)2.CuSO4 is insoluble).
At the excess of ammonia nitrate is a spectator ion.
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Offline Schrödinger

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Re: How does Copper(II) nitrate react with Ammonia?
« Reply #5 on: November 04, 2010, 01:41:38 PM »
Guess I didn't know that   :-[  :P
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