Copper (I) Cyanide solubility
DB
Is there anything else that Copper I Cyanide is soluble in besides a basic
solution(pH>10)of NaCN?
I've done quite a bit of looking on google and the newsgroups and such and
come up with the following info:
1) completely insoluble in H20
2) starts to dissolve if more NaCN is added forming higher complexes like
Cu(CN)2, Cu(CN)3 etc
3) solubility increases as pH increases.
When I added NaOH to my solution, some of the copper cyanide did dissolve,
but not to any great degree...
What could be added to the solution to dissolve this thick, green mass of
copper cyanide besides more NaCN as I don't have any?
Any hints?
Bernhard Kuemel
>
> What could be added to the solution to dissolve this thick, green mass of
> copper cyanide besides more NaCN as I don't have any?
If you don't mind your CN being bond
Fe+++ + 6 CN- ---> Fe(CN)6---
might help.
2 CuCN + H2SO4 ---> CuSO4 + 2 HCN (gas b.p. 26 C, poison)
will definitely solve all your problems :). BTW, if you don't mind
about the copper,
HCN (from above) + NaOH ---> NaCN + H2O
Oxidising Cu(I) to Cu(II) (maybe even with air) will IMO increase the
solubility.
It is probably also soluble in fused sodium acetate.
Bernhard
PS: Sorry for not posting the MSDS for Fe+++, CN-, CuCN, H2SO4, HCN,
NaOH, NaCN, Dihydrogenmonoxide, air, NaAc. Look them up yourself,
arrogant pricks, assholes and chemical laymen.
Bernhard Kuemel
> > What could be added to the solution to dissolve this thick, green mass of
> > copper cyanide besides more NaCN as I don't have any?
Cu++ + 4 NH3 ---> Cu(NH3)4++ (soluble)
so
Cu(CN)2 + 4 NH3 ---> Cu(NH3)4++ + 2 CN-
I'm not so sure if this works for Cu(I), though.
> Oxidising Cu(I) to Cu(II) (maybe even with air) will IMO increase the
> solubility.
So we heard that CO2 in air may release HCN. Take care. OTOH the
oxidation needs some acid and if there's none it will take hydroxylic
acid (HOH) which will precipitate Cu(OH)2. Gotta go now. Work it out
yourself.
Bernhard
Uncle Al
Cu(I) compounds readily dissolve in soft Lewis bases - acetonitrile,
benzonitrile, and nitriles in general; isonitriles, phosphines,
concentrated thiourea in water, thioethers...
The color should be white.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!
Ian Gilmore
Rubber Handbook gives aqHCl (care) and aq NH3 as well as KCN. See if
you can find a product data sheet from one of the suppliers.
Ian
Betty Swalls
copper(I).
The problem is that cyanide is an awfully strong ligand for Cu(I), and
CuCN is very insoluble, as you say. Maybe you need a phosphine
co-ligand, which usually implies you need to get out of water and into
another solvent - like acetonitrile, for instance. So
triphenylphosphine in acetonitrile is one way to go, but I'd just give
up and start with another source of copper(I) if I were you - cheaper
alternative.
B.S.
In article <ACDO8.12717$Hj3....@newsfeeds.bigpond.com>,
DB
metals from a used stripping solution. What we do in the jewellery trade is
to chemically strip the made jewellery with a cyanide solution just before
the final polishing stage ( I'm no stranger to using KCN).
After about a year of collecting this solution, we (or should I say I) have
the job of precipitating out the gold, silver and copper with a more
electropositive metal. The solution is a bluish purple, but at the bottom
of the container there is always a green and off white sludge. I can get
the metals out of the liquid solution alright, but have been told there is
more metal in the form of that sludge...
So thats why I wondered how I can somehow get that sludge to dissolve in the
above liquid. The nitriles may work to dissolve the copper cyanide but will
the precipitation work in that medium?
By the way, I'm not in the Jewellery industry anymore, but still do the
metal refining for them as a favour.
thanks again for the responses.
Dan
"Betty Swalls" <TBA...@yahoo.com> wrote in message
news:TBAPF6-238042....@news.comcast.giganews.com...
Uncle Al
>
> What I'm actually doing to be asking this question, is precipitating the
> metals from a used stripping solution. What we do in the jewellery trade is
> to chemically strip the made jewellery with a cyanide solution just before
> the final polishing stage ( I'm no stranger to using KCN).
>
> After about a year of collecting this solution, we (or should I say I) have
> the job of precipitating out the gold, silver and copper with a more
> electropositive metal. The solution is a bluish purple, but at the bottom
> of the container there is always a green and off white sludge. I can get
> the metals out of the liquid solution alright, but have been told there is
> more metal in the form of that sludge...
>
> So thats why I wondered how I can somehow get that sludge to dissolve in the
> above liquid. The nitriles may work to dissolve the copper cyanide but will
> the precipitation work in that medium?
Try thiourea to bring it up in aqueous solution, then bring down the
precious metal with a reducing agent. Nitric acid will chew it up,
but you must worry about HCN and NCCN off-gassing (exceedingly toxic).
DB
see how that goes.
I think the plating method of removing the metals from solution will work,
but precipitation with zinc metal is a hell of alot faster. I appreciate
your concern over the release of HCN gas from the solution, but rest assured
that I realise and understand the link between acids, cyanide compounds and
death. :) I've done 3 years of applied chem at tertiary level...although I
still dont have my diploma and rapidly forgeting what I previously learnt
:( Maybe one day I'll be back at school to finish that off.
I also use Aqua Regia sometimes to refine some gold alloys to corresponding
chlorides and later to 24k(actually 99.9 fineness)...It also is nasty stuff,
but with proper safety precautions alot less poisonous than KCN,HCN etc,
although its damn corrosive stuff!!!( Cl2 gas isn't very pleasant! )
Thanks again for the suggestions and concern...
Daniel
"Andrew Tweddle" <sar...@alphalink.com.au> wrote in message
news:3D0DDAD6...@alphalink.com.au...
> Andrew Tweddle wrote:
> > This is not a good area to go experimenting in.
> >
> > You run the risk of forming hydrocyanic gas , and gassing yourself to
> > death. Before you die you will smell almonds.
> >
> > If you must know the answer read about it in books on plating. Cyanide
> > plating of gold is still done but most other forms of cyanide plating
> > have been abandoned.
> >
> > 2NaCN +CO2 +h2O = Na2CO3 + 2HCN
> >
> > ie Don't blow air through it.
> >
> > The reaction is retarded by adding NaOH
> >
> > Also
> >
> > 2NaCN +2H2O + 2NaOH = 2Na2CO3 + 2NH3
> >
> > ie It forms ammonia when alkaline.
> >
> > All in all why are you here asking this question. This is one case where
> > I would strongly recommend you know the results before you do the
> > reaction. And knowing the results find a much safer way to get the
> > result you need.
> >
> > A horror story to set your mind on the right track.
> > As told by a plating chemist.
> >
> > One day a pretty young girl wished to go to the ball. And so headed off
> > to the Haberdashery to buy a pretty new dress. It was a beautiful green.
> > She danced the night away and felt very light headed. Next day she was
> > found dead.
> > The moral of the story is don't go dancing in a dress dyed in Copper
> > Cynanide (whatever the complex).
>
> The traditional platers approach to cyanide was just a tad
> lackadaisical.
>
> This may help
>
> Add Rochelle salt (Sodium pottasium tartrate) NaKC4H4O2.4H2O this was
> used as the way of allowing higher current plating as it forms complexes
> with the copper.
> If you find it hard to get then make it up by adding cream of tartar
> (pottasium hydrogen tartrate) to sodium hydroxide in a concentrated
> solution(aq) in a stoicimetric 1:1 ratio.
> Add to the cyanide slowly noting what the pH does, if it starts to go
> acid add a little NaOH to counteract.
>
> When you are ready to plate out warm the solution. This was done due to
> your aforementioned problem with solubility
>
> Then plate out the copper leaving your other more expensive metals
>
> Another approach would be the non-competing ion from my previous
> approach which was ammonia as it is a great complexe for copper I and II
> and gold III but I have not tried this and do not recommend
> experimenting with cyanide (this would have to be done with a fume hood,
> this will stink).
>
> I have plated from ammonia but without cyanide.
>
> It may not be clear from all the competing posts but when your solution
> turns acid it gives off HCN and God Help You. I would strongly advise
> that you do this with a pH meter always in the Solution with a nice big
> scale so you can watch from a distance.
>
> Nowadays you would probably be required to run a tank with a surrounding
> overflow tank. A double shielded air vapor trap set of lids. A suction
> to outside air to remove the ammonia fumes.
>
> My approach to your problem is give up on the cyanide.
>
> Plate it out electolytically onto a stainless electrode with a carbon
> anode at a high voltage.
> Then restart in a new solution.
>
> There is a company that sells a system for recovery of gold, platinium,
> high value metals using that other real nasty stuff aqua regia.
>
>
>
> This was one web site http://shorinternational.com/goldrecovery.htm
> using cyanide and selective plating, aqua regia etc, etc, etc. (apologys
> to Yul Bruhner):)
>
> Maybe my previous post on this was a tad unclear but I was under the
> impression you were probably trying to plate using this solution
> industrially cyanide is almost dead except for very limited use as a
> strike onto some metals where the electropotential is such that the
> copper tends to immersion or eletroless plate making for poor adhesion
> onto the base metal.