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Topic: Salt bridge  (Read 12238 times)

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Offline UG

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Re: Salt bridge
« Reply #15 on: November 07, 2009, 02:33:28 AM »
Where does the role of salt bridge ions come here.
What I thought of this line in Wikipedia is that the Zn2+ ions move to the Cu electrode and neutralize the SO42- ions and the SO42- ions move to the Zn electrode and neutralize the Zn2+ ions.

Is this right?

Yes, well initially, you would still need the salt bridge to complete the circuit or else the reaction won't even get started, after a while, I suppose the different ions can move all over the place and keep the half-cells neutral. That's all I've got I'm afraid  :-\

Offline Schrödinger

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Re: Salt bridge
« Reply #16 on: November 07, 2009, 02:34:02 AM »
Since the Zn rod is negatively charged with respect to the solution, will there not be a layer of Zn2+ around this rod due to opposite charge attraction?

This is quite an absurd question.
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Offline UG

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Re: Salt bridge
« Reply #17 on: November 07, 2009, 02:36:55 AM »
Since the Zn rod is negatively charged with respect to the solution, will there not be a layer of Zn2+ around this rod due to opposite charge attraction?

This is quite an absurd question.
Huh? Sorry mate, you're just confusing me even more about what you are asking  ???
Of course there will be Zn2+ ions around the rod because they are constantly being produced by the oxidation of zinc

Offline Schrödinger

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Re: Salt bridge
« Reply #18 on: November 07, 2009, 02:39:39 AM »
It's alright. Let's drop the question.

About your reply to arjunarul's post....
So, you mean we can find some ZnSO4 in CuSO4 beaker?
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Offline Schrödinger

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Re: Salt bridge
« Reply #19 on: November 07, 2009, 02:43:50 AM »
Since the Zn rod is negatively charged with respect to the solution, will there not be a layer of Zn2+ around this rod due to opposite charge attraction?

This is quite an absurd question.
Huh? Sorry mate, you're just confusing me even more about what you are asking  ???
Of course there will be Zn2+ ions around the rod because they are constantly being produced by the oxidation of zinc


So, do we use the salt bridge to prevent this build up of Zn2+ layer around the Zn rod?
"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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Offline UG

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Re: Salt bridge
« Reply #20 on: November 07, 2009, 02:47:00 AM »
So, you mean we can find some ZnSO4 in CuSO4 beaker?
Well Wikipedia basically said it. Zn2+ ions by the way, sulfate ions were already there to start off with.

So, do we use the salt bridge to prevent this build up of Zn2+ layer around the Zn rod?
Yes, the nitrate ions takes care of this

Offline Schrödinger

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Re: Salt bridge
« Reply #21 on: November 07, 2009, 02:49:08 AM »
Got it!

Thanx mate...I'm giving you a mole snack... :)
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Offline UG

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Re: Salt bridge
« Reply #22 on: November 07, 2009, 03:03:18 AM »
Thanks man  ;D
Good luck!

Offline arjunarul

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Re: Salt bridge
« Reply #23 on: November 07, 2009, 03:10:55 AM »
I'll tell what I understood now. Please tell if it is right.

Both the processes take place:

1. K+ and Cl- ions go to the opposite ends of the salt bridge ( K+ near the oxidative part and Cl- near the reductive part).
So, the Zn2+ ions come near the salt bridge and so, it does not accumulate near the electrode, thus allowing free electron flow. Similarly for the the other part.

2. The Zn 2+ ions move to the reductive half and the SO42- ions go to the oxidative part. This neutralizes the excess charge.

Some Zn2+ ions undergo first process while others undergo second process.


Offline UG

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Re: Salt bridge
« Reply #24 on: November 07, 2009, 03:18:27 AM »
I'll tell what I understood now. Please tell if it is right.

Both the processes take place:

1. K+ and Cl- ions go to the opposite ends of the salt bridge ( K+ near the oxidative part and Cl- near the reductive part). The other way round, K+ moves to the cathode
So, the Zn2+ ions come near the salt bridge and so, it does not accumulate near the electrode, thus allowing free electron flow. Similarly for the the other part. Yes

2. The Zn 2+ ions move to the reductive half and the SO42- ions go to the oxidative part. This neutralizes the excess charge. I am not sure about SO42-, the concentration should be 1 mol L-1 in each half-cell so there shouldn't be any net movement

Some Zn2+ ions undergo first process while others undergo second process.

Offline arjunarul

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Re: Salt bridge
« Reply #25 on: November 07, 2009, 05:11:59 AM »

1. K+ and Cl- ions go to the opposite ends of the salt bridge ( K+ near the oxidative part and Cl- near the reductive part). The other way round, K+ moves to the cathode
Sorry, it was silly of me.

2. The Zn 2+ ions move to the reductive half and the SO42- ions go to the oxidative part. This neutralizes the excess charge. I am not sure about SO42-, the concentration should be 1 mol L-1 in each half-cell so there shouldn't be any net movement
Ok. But it was given like that in Wikipedia right??

So, according to you, it's something like diffusion of ions due to difference in concentrations right? So, if we use ZnCl2 and CuSO4, concentration of SO4 is zero in the other half. So, will they start diffusing through the salt bridge till they become evenly distributed???

I guess that I am terribly wrong somewhere.

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