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Topic: Al + HCl  (Read 17809 times)

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Offline lutesium

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Al + HCl
« on: December 15, 2007, 05:34:19 AM »
Dear Sir/Ma'am

What occurs when Al metal is reacted w/HCl??? I've always thought that AlCl3 formed but this is not the case! I've got one more question: Why does a flash of light occur when is dipped over Al metal??? As far as I know ligtning occurs when electrons jump over the higher energy level (by exication) and then returns to its normal level but why may Br2 cause this type of exication???


Lutesium...
 
« Last Edit: December 15, 2007, 05:46:32 AM by lutesium »

Offline Sev

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Re: Al + HCl
« Reply #1 on: December 15, 2007, 06:24:16 AM »
Quote
What occurs when Al metal is reacted w/HCl??? I've always thought that AlCl3 formed but this is not the case!

Why?
Al0 + HCl → AlCl3 + H2

oxide layer may first need to dissolve.  No idea for 2nd question.

Offline RBF

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Re: Al + HCl
« Reply #2 on: December 15, 2007, 07:58:52 AM »
If the reaction is done in an aqueous environment (as is likely), the AlCl3 (being a Lewis acid) will react with the water, so AlCl3 will not be isolated

Offline lutesium

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Re: Al + HCl
« Reply #3 on: December 15, 2007, 10:48:36 AM »
So we can say that

2Al + 6HCl => 2AlCl3 + 3H2

AlCl3 + 3H2O => Al(OH)3 + 3HCl

Thanx for the *delete me*!!


Lutesium...

Offline lutesium

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Re: Al + HCl
« Reply #4 on: December 18, 2007, 11:25:24 PM »
But if the RXN scheme is as I proposed only catalytic amounts of HCl would suffice! Cuz If the formed AlCl3 brings out 3HCl this HCl would reduce 1Al bringing out 1AlCl3 then that'll bring 3HCl and things will go on like that!!!

And for my second question anyone knows the answer???


Lutesium...

Offline RBF

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Re: Al + HCl
« Reply #5 on: December 19, 2007, 12:10:34 AM »
Aluminum chloride forms hydrates with water, for example aluminum chloride hexahydrate.  This can undergo partial hydrolysis to HCl.  I suspect that  a mixture of aluminum species are formed in aqueous solution, including AlCl4- and various hydrated species.  An inorganic chemist could probably supply more details.  But not all of the Cl will be regenerated as HCl.

Offline lutesium

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Re: Al + HCl
« Reply #6 on: December 19, 2007, 10:18:25 AM »
Thanx RBF but if that is the case so we can say that some AlCl3 is produced in the process I'm really puzzled!!! Help me!!!


Lutesium...

Offline RBF

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Re: Al + HCl
« Reply #7 on: December 19, 2007, 11:48:20 AM »
In the presence of water (e.g. aq. HCl) there will not be any 'anhydrous' AlCl3 present.  In fact, in aqueous HCl, there really isn't much 'HCl'; it dissociates to H3O+ and Cl-. What you probably have is a solution of hydrated Al+3 ions, chloride ions, AlCl4- complex ions and aluminum chloride hexahydrate, with perhaps other mixed and hard to characterize species present. 
The life time of 'AlCl3' will be very small.  So I guess you can say it is produced, but good luck isolating it.

Offline Hand15

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Re: Al + HCl
« Reply #8 on: December 19, 2007, 12:53:46 PM »
Well certainly it is hard to have AlCl3 isolated if the reaction occured in aqueos formed.

Why not using gas?

2Al +3Cl2 → 2AlCl3

or

2Al + 6 HCl → 2 AlCl3 + 3 H2
Here HCl is hydrogen chloride not hydrochloric acid

But becareful handling them ;D

Offline lutesium

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Re: Al + HCl
« Reply #9 on: December 20, 2007, 12:11:17 AM »
I KNOW that AlCl3 can be made at very high tempratures by using Chlorine gas + Al but here we don't talk about how to make AlCl3 we are talking about the reaction of HCl + Al!!! Be reasonable please...

Oh my goodness I really didn't know that it wasn't Hydrogen Chloride :)


Lutesium...

Offline Borek

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Re: Al + HCl
« Reply #10 on: December 20, 2007, 03:07:24 AM »
What you call AlCl3 in aqueous solution looks more like Al(H2O)63+ + 3Cl- - there is no such thing as free (not hydrated) Al3+.

Even that picture is a simplification :)
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Offline lutesium

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Re: Al + HCl
« Reply #11 on: December 20, 2007, 07:06:39 AM »
Would real AlCl3 react with H2O to release HCl gas??? As far as I can remember AlBr3 reacted with H2O to release HBr gas so there can't be any aquaeous AlCl3 solution!!!

Help me please... ???


Lutesium...

Offline AWK

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Re: Al + HCl
« Reply #12 on: December 20, 2007, 07:47:44 AM »
Hydrolysis is an equilibrium reaction. for anhydrous AlCl3 you can observe its decomposition in (wet) air (fumes and smell).
AWK

Offline lutesium

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Re: Al + HCl
« Reply #13 on: December 20, 2007, 11:29:38 PM »
So what is the answer of my question??? Does AlCl3 form or not???

Thanks to you all for your concern!!!


Lutesium...

Offline AWK

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Re: Al + HCl
« Reply #14 on: December 21, 2007, 03:31:55 AM »
So what is the answer of my question??? Does AlCl3 form or not???

Thanks to you all for your concern!!!


Lutesium...
In solution exist Al(H2O)63+ and Cl-

When you evaporate water with conc. HCl added to solution you can obtain solid AlCl3.6H2O. Without addition of HCl you will obtain nonstoichiometric mixture of AlCl3 with Al(OH)3
AWK

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