IceDahl
Harmless
Posts: 22
Registered: 28-2-2016
Member Is Offline
Mood: Curious
|
|
Copper and Ammonia
Is it possible to dissolve copper or at least copper compounds in ammonia. What would i get if i dissolve for example copper chloride in ammonia. I
could not find much info about this.
Note: By ammonia i mean ammonia in a water solution.
|
|
|
Amos
International Hazard
Posts: 1406
Registered: 25-3-2014
Location: Yes
Member Is Offline
Mood: No
|
|
Yes, copper compounds will dissolve in aqueous ammonia with few exceptions. If you were to add ammonia solution to a solution of copper(II) chloride,
you'd first encounter a pale blue precipitate of copper(II) hydroxide, and the supernatant would contain ammonium and chloride ions. With some
stirring and the addition of more ammonia, the copper(II) hydroxide will dissolve to yield a deep royal blue color indicative of the copper(II)
tetraammine complex, [Cu(NH3)4]2+, and the ammonium and and chloride ions from earlier will still be present in the solution as well as some hydroxide
ions.
|
|
|
PHILOU Zrealone
International Hazard
Posts: 2893
Registered: 20-5-2002
Location: Brussel
Member Is Offline
Mood: Bis-diazo-dinitro-hydroquinonic
|
|
If you put copper wire with aqueous ammonia and air into a closed recipient with a screew on top.
Shake it from time to time and open to allow fresh air to enter (oxygen is consumed by the reaction)...the ammonia solution will turn bluer and bluer
with time...you finally end up with dark blue Cu(NH3)4(OH)2 ...the crystals of those burn with a blue-green flame.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
|
|
|
aga
Forum Drunkard
Posts: 7030
Registered: 25-3-2014
Member Is Offline
|
|
I tried that with a piece of copper pipe suspended above some conc ammonia.
The Blue colour of the drop of liquid that forms under the copper pipe is the most beautiful blue i have ever seen.
|
|
|
MeshPL
Hazard to Others
Posts: 329
Registered: 20-4-2015
Location: Universe
Member Is Offline
Mood: No Mood
|
|
Electrolysis of copper electrodes in ammonia solution also produces tetraaminacopper (II) hydroxide, although after some point the copper starts
plating on the cathode and reaction practically stops. Could be an interesting way to do copper plating though.
|
|
|
moonfisher
Harmless
Posts: 27
Registered: 15-2-2016
Member Is Offline
Mood: No Mood
|
|
I second aga, it is a stunning blue, like the finest gentiana. Sometimes, copper (ii) boride looks a little like it, but not really.
Well, good chemists shouldn't lick their fingers, anyways
-Life advice from Sir Martyn
|
|
|
chemrox
International Hazard
Posts: 2961
Registered: 18-1-2007
Location: UTM
Member Is Offline
Mood: LaGrangian
|
|
Quote: Originally posted by MeshPL  | | Electrolysis of copper electrodes in ammonia solution also produces tetraaminacopper (II) hydroxide, although after some point the copper starts
plating on the cathode and reaction practically stops. Could be an interesting way to do copper plating though. |
Would this be a PTC? and could one use Cu/NH4 in dissolving metal reductions?
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
|
|
|
Metacelsus
International Hazard
Posts: 2531
Registered: 26-12-2012
Location: Boston, MA
Member Is Offline
Mood: Double, double, toil and trouble
|
|
The reducing potential of Cu is not very good, when it comes to reducing organic compounds. In fact, copper(ii) is sometimes used as an oxidant (for
example, in Fehling's solution / Benedict's reagent).
[Edited on 3-12-2016 by Metacelsus]
|
|
|
AJKOER
Radically Dubious
Posts: 3026
Registered: 7-5-2011
Member Is Offline
Mood: No Mood
|
|
A source reference detailing the underlying mixed chemistry involving Cu/NH3/H2O/O2 or H2O2 and a touch of sea salt, which is a good electrolyte for
the spontaneous electrochemical aspects of the reaction. Interestingly, the mechanics of the reaction was debated by pundits for many decades. The
link below also contains a picture of some of my efforts:
https://www.sciencemadness.org/whisper/viewthread.php?tid=64...
Warning: Do not apply an electric current to an ammonia solution in air and allow the pH to drop. Apparently, an acidified NH4NO2 solution is prone to
detonation such that researchers avoid such situations. See my prior comments on this topic at https://www.sciencemadness.org/whisper/viewthread.php?tid=63...
[Edit] Similar comments per Wikipedia on NH4NO2, to quote:
"Ammonium nitrite solution is stable at higher pH and lower temperature. If there is any decrease in pH lower than 7.0, It may lead to explosion. It
is desirable to maintain pH by adding ammonia solution. "
Link: https://en.m.wikipedia.org/wiki/Ammonium_nitrite
[Edited on 21-3-2016 by AJKOER]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
