[pc_game_lover2004]

Could anybody please tell me that anode losses electrons and still anode is negative whereas cathode gains electrons and it is positive why is it so....

[Kuahji]

I think they just do that because of the "flow" of electrons.  The electrons come from the anode...  its always a bit confusing at first.   

[Borek]

Anode doesn't loose electrons. Current flows in the opposite direction to electrons. Anode attracts anions. These are usually electron rich and can leave their electrons on the anode. OTOH cathode attracts cations - these are usually electron deficient and will accept electrons willingly.

[pc_game_lover2004]

I'm still not getting it please explain in detail...

From where these anions and cations come from...

I'm using a simple galvanic cell with zn as electrode in zinc sulphide and copper as electrode in copper sulphide along with salt bridge containing agar-agar saturated with KCl.

Now please explain me how the anode is -ve and cathode is +ve...

[Valdorod]

[pc_game_lover2004]

I'm still nowt getting the proper answer as to why anode is -ve and cathode is +ve..

[Borek]

I'm still nowt getting the proper answer as to why anode is -ve and cathode is +ve..

No idea what is it that still confuses you, so it is hard to help. Please elaborate.

[cliverlong]

I'm still not getting it please explain in detail...

From where these anions and cations come from...

I'm using a simple galvanic cell with zn as electrode in zinc sulphide and copper as electrode in copper sulphide along with salt bridge containing agar-agar saturated with KCl.

Now please explain me how the anode is -ve and cathode is +ve...

I sympathise with you.

I always have trouble remembering the meaning of anions and cations.

I think the core of your misunderstanding is the concepts of electrolysis and the electrochemical cell have become mixed. I think this is easy to do because I rarely see the distinction in naming made clear.

First, I would forget about names and understand the excellent picture, provided by Valdorod, on the behaviour of the Zn/Cu electrochemical cell. Take time to understand the behaviour of every charged species.

2. Now go back to electrolysis. There is a negatively charged electrode called the cathode and a positively charged electrode called the anode.
Positive ions (e.g. Zn²⁺ or Na⁺) are attracted to the negative electrode (cathode) and are called cations
Reduction is gain of electrons
So reduction happens at the cathode << This is key
Negative ions (e.g. SO₄^2- Cl^-) are attracted to the positive electrode (anode) and are called anions
Oxidation is loss (Edit: corrected) of electrons
So oxidation happens at the anode << This is key

3. Now consider the electrochemical cell in the diagram above.

Zinc is equilibrium with zinc ions

Zn <>  Zn²⁺ + 2e^-

The equilibrium is to the right (because of relative electrode potential to copper)

Now the Zn²⁺ can only go into the solution and the e^- goes up the wire
Now, Zn is being converted to  Zn²⁺ by losing electrons , so the electrode is being oxidized so this is the anode

Conversely, at the other electrode (I haven't named it yet)

Cu²⁺ is taken out of solution by adding electron that has come from the wire.
Now, Cu²⁺ is being converted to  Cu by gaining electrons , so the electrode is being reduced so this is the cathode

Overall in the cell Zn electrode provides electrons to the circuit but is called anode, Cu²⁺ is discharged and deposited at the electrode that is receiving electrons that is called the cathode

Hope that helps (hope it's correct ! )

Try also here

http://en.wikipedia.org/wiki/Electrochemistry

P.S. I retyped this entry 10 times because of errors - and I'm still not 100% confident !!

P.P.S You originally wrote sulfide/sulphide but in aqueous solution the species would be sulfate/sulphate.

[pc_game_lover2004]

Sorry My mistake.. It's Sulphate....

well you made it to me 100% clear so...Thank you very much...

Here from me....

What are those scooby snacks....

anyways if you have to be voted for moderator etc. do tell me i'll vote you...

well in this is the key...
you have written both oxydation and reduction as the gain of electrons...

[cliverlong]

well in this is the key...
you have written both oxydation and reduction as the gain of electrons...

Oops !!! 

I wish I could claim it was a deliberate mistake to test people reading the post !!!

Shoot the proof reader !

Can a moderator edit my entry and also make Cu2+ into superscript?

Also for activity at Cu cathode (ha ! ) can text be changed to "reduction occurs at the cathode" rather than "the cathode is reduced" ??

Ta

Clive

[pc_game_lover2004]