Nickel purification help

[jdurg]

Is it possible that some nickel metal actually plated onto the aluminum foil and remained 'stuck' there instead of falling off like expected? Then once the nickel had covered the aluminum, no more reaction could occur? That could also explain why it reacted with the copper sulfate so well since copper is presumably below nickel in the electromotive series. With the copper sulfate being an intense blue, it would be hard to see any green from the nickel.

[budullewraagh]

oh good call. yt, what sort of Al did you use? i suggest you try a powder if you didnt before

[YT2095]

Jdurg , it didn`t, I checked.

I wish it were just as simple as that

 

Bud, I`m trying different alu sources (as of about 4 hours ago) still nothing!

 

although I AM surprised at the amount of Cd metal contamination in the soln, I really never considered it to be that high, but all that glitters green is not Gold (or something like that)

[YT2095]

well after such a great success with the Tin Metal extraction, I though I`de employ a similar procedure to this Nickel problem I`de had some time ago.

for some reason the nickel sulphate I had didn`t want to electrolise at all and plate out, so I mixed up a soln of NaOH, and added this to the sulphate (the Bicarb didn`t have any effect), I got the Nickel Hydroxide gell, it was then filtered and washed. then I added HCl to dissolve it all again making nickel chloride soln.

I`m happy to say that this soln DOES plate out Nickel metal (and Chlorine).

the process is alot slower than the tin metal, and I`m not getting the nice crystal structures, but at a low voltage (4 volts) and using carbon electrodes, there is definate shiny metalic particles around the Cathode.

 

so this is Another project completed and put to bed

[xeluc]

I'm sorry if this is obvious.. but can you displace ANY hydroxide with HCl? If so, I can finally do a test I have been wanting to do.

[woelen]

I'm sorry if this is obvious.. but can you displace ANY hydroxide with HCl? If so, I can finally do a test I have been wanting to do.

Only the basic ones and amphoteric ones (the hydroxides of metals in lower oxidation states). Higher oxidation state hydroxides may be a problem (e.g. SnO(OH)2, stannic acid) some are even impossible (e.g. SiO(OH)2, silicic acid).

 

Beware, however, that some basic hydroxides may be remarkably inert and although in theory they dissolve, in practice they only dissolve with very great difficulty.

[xeluc]

i mean like.. Cu Fe Ni Zn just the simple ones

[akcapr]

how can a SiO(OH)2 or SnO(OH)2 be anm acid? (the OH group n all)

[woelen]

how can a SiO(OH)2 or SnO(OH)2 be anm acid? (the OH group n all)

The properties of an OH group depend in the atom, to which it is connected.

 

With compounds like NaOH and KOH, the OH group in fact is a separate ion OH(-). These are purely basic.

 

In a compound like Al(OH)3, the OH-groups are not purely ionic, they are bound to the Al-atom somewhat covalently, there is an Al-O bond. When this compound is added to a strongly acidic solution, then it acts as base:

 

Al(OH)3 + 3H(+) ---> Al(3+) + 3H2O

 

When this compound is added to a strongly alkaline solution, then it acts as acid:

 

Al(OH)3 + 3OH(-) ----> AlO3(3-) + 3H2O

 

So, here you see that the OH-groups act as acid, by splitting off a H(+).

 

The compound B(OH)3 is purely acidic, it cannot split off OH(-) ions, but it can split off H(+), albeit only in strong alkalies.

 

A rule of thumb exists:

 

The more electroposive a metal, the more basic the compound M(OH)n. If a metal exists in multiple oxidation states, then the metal hydroxide for the highest oxidation state is the least basic.

 

At high oxidation states, the hydroxides are acidic, e.g. SO2(OH)2 is a very strong acid, NO2(OH) also is. These are sulphuric acid and nitric acid.

 

For Xeluc: The metals you mentioned, these hydroxides can be dissolved without problem in HCl. The oxides may be a different story. E.g. Cr2O3 cannot be dissolved in any aqueous liquid, no matter how acidic, once it is calcined. Fe2O3 only dissolves with VERY great difficulty, once it is calcined.