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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: kingkurry on November 02, 2010, 10:18:01 PM

Title: How does Copper(II) nitrate react with Ammonia?
Post by: kingkurry 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?
Title: Re: How does Copper(II) nitrate react with Ammonia?
Post by: AWK on November 03, 2010, 06:09:56 AM
[Cu(H2O)4]2+ + 4NH3 = [Cu(NH3)4]2+ + 4H2O
Title: Re: How does Copper(II) nitrate react with Ammonia?
Post by: Schrödinger 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
Title: Re: How does Copper(II) nitrate react with Ammonia?
Post by: rabolisk on November 03, 2010, 10:11:11 AM
The nitrates are spectator ions.
Title: Re: How does Copper(II) nitrate react with Ammonia?
Post by: AWK on November 03, 2010, 12:25:14 PM
Quote from: Schrödinger 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

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.
Title: Re: How does Copper(II) nitrate react with Ammonia?
Post by: Schrödinger on November 04, 2010, 01:41:38 PM
Guess I didn't know that   :-[  :P