Sciencemadness Discussion Board

Chromium/Nickel Chlorides?

arkoma - 21-5-2014 at 12:23

I've been running a flower pot salt bridge cell (per King's Chemistry Survival Guide)to make my own NaOH and using a carbon cathode electrode and a cheap stainless steel butter knife anode electrode. The anodic liquid is a dark emerald green and i've been chipping off iron oxide from inside the pot when I service it.

After going here and looking at Woelens wonderful pictures I have come to the conclusion that I have a mixture of Cr/Ni chlorides. I'm a beginner but this seems to me to be a correct conclusion.

My question is, am I correct? And if so, can I separate the salts?

thesmug - 21-5-2014 at 15:19

Yes, you are correct. Separating the salts might be hard. If you want to separate the ions chemically just electrolyze the mixture (warning: chlorine). If you want to keep the salts together (as solid Ni/Cr chloride) you could dry the mixture and try to separate them by solubility in other solvents. I can't think of any other methods at the moment, surely someone else will be able to help more!

[Edited on 5/21/14 by thesmug]

The Volatile Chemist - 21-5-2014 at 17:32

I am completely unfamiliar with this procedure, could someone fill me in? I do know that Chromium and nickel form complexes differently, maybe they could be used. Woelen would know.

thesmug - 21-5-2014 at 18:08

I know that nickel chloride forms ammine complexes (hexaaminenickel(ii) chloride is one) but I don't believe that chromium does. Let's keep using hexaamminenickel(ii) chloride. Hexaamminenickel(ii) chloride separates nicely from water on addition of acetone and chromium chloride is insoluble in acetone so if you add concentrated ammonia and then add a bit of acetone it should layer into water|chromium chloride|hexaamminenickel(ii) chloride. That diagram might not be right but hexaamminenickel(ii) chloride is a vivid lilac color so it should be easy to differentiate. From here separation is very easy. I'll try this sometime to see if I'm right.

The Volatile Chemist - 21-5-2014 at 18:13

Quote: Originally posted by thesmug  
I know that nickel chloride forms ammine complexes (hexaaminenickel(ii) chloride is one) but I don't believe that chromium does. Let's keep using hexaamminenickel(ii) chloride. Hexaamminenickel(ii) chloride separates nicely from water on addition of acetone and chromium chloride is insoluble in acetone so if you add concentrated ammonia and then add a bit of acetone it should layer into water|chromium chloride|hexaamminenickel(ii) chloride. That diagram might not be right but hexaamminenickel(ii) chloride is a vivid lilac color so it should be easy to differentiate. From here separation is very easy. I'll try this sometime to see if I'm right.

TheHomeScientist has posted on something similar, what you said makes sense.

thesmug - 21-5-2014 at 18:16

He was the one who suggested I make some hexaaminenickel(ii) chloride a while back so that's why I'm so fond of that chemical in this example. One of my favorite syntheses ever! It's probably the easiest synthesis ever.

DraconicAcid - 22-5-2014 at 09:16

If you make the solution basic enough, nickel hydroxide will precipitate out, and a complex chromium ion will remain in solution.

Zyklon-A - 22-5-2014 at 09:36

Chromium from SS

arkoma - 22-5-2014 at 10:58

Quote: Originally posted by DraconicAcid  
If you make the solution basic enough, nickel hydroxide will precipitate out, and a complex chromium ion will remain in solution.


Seems Ni(OH)2 is not only carcinogenic but is pretty damn toxic, too..

Quote from here
Quote:
Toxicity[edit]
The Ni2+ ion is a known carcinogen in both humans and mice, possibly by entry into cells via phagocytosis [8]. In the CHO cell line, Ni(OH)2, the LC50 dose has been shown to be 3.6 μg/ml. This high level of toxicity relative to other Ni2+ containing compounds is hypothesized to be due to the insoluble nature of the compound, and concentration in the nucleus.[11] Toxicity and related safety concerns have driven research into increasing the energy density of Ni(OH)2 electrodes, such as the addition of calcium or cobalt hydroxides.[2]


Maybe I'll have enough sense to leave this one alone....

The Volatile Chemist - 22-5-2014 at 12:42

Quote: Originally posted by DraconicAcid  
If you make the solution basic enough, nickel hydroxide will precipitate out, and a complex chromium ion will remain in solution.


Obviously one of the simplest solutions to the problem.
Quote:

Seems Ni(OH)2 is not only carcinogenic but is pretty damn toxic, too..


Indeed! Be careful.

thesmug - 22-5-2014 at 19:37

I particularly hate nickel compounds because working with them has made me extremely paranoid about getting cancer. Be careful OP!