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Topic: Synthesis of Copper (II) Acetate Question  (Read 9117 times)

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Offline interminable

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Synthesis of Copper (II) Acetate Question
« on: March 26, 2010, 02:50:56 PM »
In lab we synthesized copper (II) acetate starting from copper (II) sulfate pentahydrate. First ammonia was added, followed by sodium hydroxide.

I've been working on the balanced equations, and I understand we're forming a Cu(OH)2 precipitate twice, (we dissolved it with excess ammonia the first time and reformed it with the NaOH).

We dissolve the Cu(OH)2 in 10% acetic acid solution to obtain the acetate product. I'm just wondering why dissolving the copper (II) sulfate directly in the acetic acid and skipping all the other steps wouldn't work.

Offline Schrödinger

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Re: Synthesis of Copper (II) Acetate Question
« Reply #1 on: March 27, 2010, 03:32:40 AM »
If you were to add acetic acid directly, then the reaction (supposing that they react) would be :

CuSO4 + CH3COOH  :rarrow: (CH3COO)2Cu + H2SO4

But as you can see, a weak acid (acetic acid) is displacing a stronger acid (sulphuric acid) from its salt. That's not possible.

On the other hand, when you add NaOH, the acid being displaced is H2O, which is certainly weaker than acetic acid. (wirte the equation)


P.S : I recently learned on this forum that there might be rare exceptions to this rule. http://www.chemicalforums.com/index.php?topic=40518.0
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Offline interminable

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Re: Synthesis of Copper (II) Acetate Question
« Reply #2 on: March 27, 2010, 12:35:32 PM »
Thanks, the answer seems obvious now, haha.
 
Cu(OH)2 + CH3COOH --> Cu(CH3COO)2 + H2O

This is what you were referring to, right?

Offline Schrödinger

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Re: Synthesis of Copper (II) Acetate Question
« Reply #3 on: March 28, 2010, 08:30:21 AM »
Yes
"Destiny is not a matter of chance; but a matter of choice. It is not a thing to be waited for; it is a thing to be achieved."
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