Sciencemadness Discussion Board

Mechanism of the Reaction of aluminum metal with nickel (II) chloride solution

Gru - 31-1-2019 at 00:06


I am planning some reactions with aluminum and nickel(II)chloride. Details of the mechanism online are scant at best, but I did find the reaction mechanism for Al and CuCl2 and wonder if both mechanisms are the analogous. This is what was found.

Reaction of aluminum metal with copper (II) chloride solution

Commonly, we would write the following 2Al(s) + 3CuCl2(aq) -> 3Cu(s) + 2AlCl3(aq)

Also, the aluminum ion in solution may be coordinated with four chloride ions: [AlCl4]1-

But that isn't the whole story.

Copper (II) ions will hydrolyze to produce an excess of hydrogen ions, making the copper (II) chloride solution slightly acidic.

Aluminum metal is always covered in a thin, but protective layer of aluminum oxide, Al2O3. The chloride ion helps to separate the aluminum from the oxygen so that the aluminum can react with the copper ions (and the water molecules).

Cu2+ + HOH -> CuOH1+ + H1+

Al2O3 + 4Cl1- + H2O + 2H1+ -> 2[Al(OH)2Cl2]1-

The reaction is also accompanied by the evolution of hydrogen gas 2Al + 6H1+ -> 2Al3+ + 3H2

Can anybody confirm that NiCl2 will do the same thing. Thanks in advance.

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oberkarteufel - 31-1-2019 at 03:00

Yes, that's pretty much the same mechanism.

Gru - 31-1-2019 at 15:09

Is that like pretty much, or exactly that?

I know the first equation 2Al(s) + 3NiCl2(aq) -> 3Ni(s) + 2AlCl3(aq) is correct but can find no information on what happens after next.

oberkarteufel - 1-2-2019 at 01:36

The same type of hydrolysis occurs as with copper, the same chloride catalysed reaction of aluminium oxide dissolution. It's analogous. The same will go iron and cobalt.
BTW. you may want to find out about "Urushibara catalyst"