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Topic: Electrolysis problem...Am I Right???  (Read 3510 times)

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Offline Electrolize

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Electrolysis problem...Am I Right???
« on: July 23, 2010, 06:53:47 PM »
A 5.0 M solution of AgNO3 (g) was electrolyzed for 6 Hr at 10 A. If the cell held 500 ML of solution (no change in volume), what were the mass of silver deposited and the concentration of Ag+ in the final solution?

So far I got this but unsure about it.

10.00 amps x 6.00 Hrs x (3600 secs / 1 Hr) = 216,000 Coulombs.

216,6000 Coul. x (1 Faraday / 96,500 Coul)  = 2.238 Faradays

2.238 Faraday x (1 Mol Ag+ / 1 F) = 2.238 Moles of Ag+

2.238 Moles Ag+ x (107.86g (Mass of Ag) / 1 Mol Ag+) = 241.39 Grams of Ag+

(2.238 Moles of Ag+ / .500 L ) = 4.476 Ag+ Concentration?

So I get 241.39g as the mass and 4.476 as the concentration of Ag+, is this correct?


Offline Schrödinger

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Re: Electrolysis problem...Am I Right???
« Reply #1 on: July 23, 2010, 11:07:54 PM »
The final mass and the final concentration are those of Ag, not Ag+. The question wants you to find the amount of  Ag+ remaining after electrolysis.
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Offline Electrolize

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Re: Electrolysis problem...Am I Right???
« Reply #2 on: July 24, 2010, 02:13:46 PM »
The final mass and the final concentration are those of Ag, not Ag+. The question wants you to find the amount of  Ag+ remaining after electrolysis.

Are you saying that to replace the Ag+ with Ag? Because the loss of a single electron shouldn't really make much of a difference since the mass of an electron is so small.

Offline Schrödinger

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Re: Electrolysis problem...Am I Right???
« Reply #3 on: July 24, 2010, 02:47:02 PM »
The final mass and the final concentration are those of Ag, not Ag+. The question wants you to find the amount of  Ag+ remaining after electrolysis.

Are you saying that to replace the Ag+ with Ag? Because the loss of a single electron shouldn't really make much of a difference since the mass of an electron is so small.

I am not referring to the single electron and trying to be pedantic. Ag+ has to replaced by Ag because that's what is correct. When you electrolyse a solution containing Ag+ ions (the source of Ag+ being AgNO3 here), Ag gets deposited, not Ag+. The metal is what gets deposited.

So, when you are reporting you're final answer :
241.39g as the mass and 4.476 as the concentration of Ag, not Ag+
Now that makes all the difference doesn't it?
 
"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."
- William Jennings Bryan

Offline Electrolize

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Re: Electrolysis problem...Am I Right???
« Reply #4 on: July 24, 2010, 03:58:08 PM »
The final mass and the final concentration are those of Ag, not Ag+. The question wants you to find the amount of  Ag+ remaining after electrolysis.

Are you saying that to replace the Ag+ with Ag? Because the loss of a single electron shouldn't really make much of a difference since the mass of an electron is so small.

I am not referring to the single electron and trying to be pedantic. Ag+ has to replaced by Ag because that's what is correct. When you electrolyse a solution containing Ag+ ions (the source of Ag+ being AgNO3 here), Ag gets deposited, not Ag+. The metal is what gets deposited.

So, when you are reporting you're final answer :
241.39g as the mass and 4.476 as the concentration of Ag, not Ag+
Now that makes all the difference doesn't it?
 

Yes it does, thank you so much.

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