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Determining Anode from Cathode (1 Viewer)

Sammy Man

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Hey guys

I was just wondering how to determine the Anode and the Cathode in a galvanic cell?
I know that oxidation occurs at the Anode, and Reduction occurs at the Cathode, but how do i tell them apart?

Your help is much appreciated, cheers.
 

EmmR

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if you took physics, just remember its back wards.
 

Nodice

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Since its a galvanic cell, the more reactive metal (as dictated by the data sheet) will be oxidised. And as well all know, OIL RIG.
 

izzy88

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ok u need ur standard potentials sheet which u get at the back of the paper...

find the one for Ag which is-
Ag(+) +e-->Ag(s) 0.80V

the one for Pb is-
Pb(2+) + 2e--> Pb(s) -0.13V

now these are both reduction eqn so u need to flip one for the oxidation...u can tell this by the volts for each one, essentially without going into technicalities u want the electrode potential E to be the highest so in this case the -0.13 is reversed to 0.13 therefore the Pb one is the oxidation equation

hence Ag is the cathode cause thats where reduction occurs and Pb is the anode cause thats where oxidation occurs....

quick note- if u also look at the standard potentials, oxidation occurs more as u are going up the table...

does that help?
 

izzy88

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ok i obviously went overly complicated on that answer....oh well!
 

Sammy Man

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Thanks very much Nodice and Izzy.

I'm starting to understand it, electrochemistry is the part of chemistry where i've always struggled a bit.

Thanks for your help :wave:
 

dral

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Bah, i always remembered from the electrical subject in year 9 that it went from negative to positive through a circuit and...

Anode
Ahh... Negative!

except in electrolysis where it's reversed.

This is a bad way to remember :D
 

airie

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Heh, I just remember the anode-cathode positivity/negativity is the reverse of anion-cation :p For ions, ones that start with "a" is negative, but for electrodes, ones that start with "a" is positive :D
 

mr coolerer

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Sammy Man said:
Thanks very much Nodice and Izzy.

I'm starting to understand it, electrochemistry is the part of chemistry where i've always struggled a bit.

Thanks for your help :wave:
Up until before the trial, electrochemistry was always a problem for me too, but my advice is this (despite the fact that it is quite late), learn to love the table of standard reduction potentials.
 

NightShadow

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this one will always work guys

AN OX rite... but oxidation is the loss of electrons... so electron are coming out of the ANODE

draw the arrow of the flow of electrons and bob's your uncle
 

angmor

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<b>R</b>eductant
<b>A</b>node
<b>L</b>oss
<b>O</b>xidation

<b> RALO </b>
 

dikeymikey

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For these type of things we use: <b>Anox Redcat</b>

<b>Anox</b> - Anode/oxidation

and

<b>Redcat</b> - cathode/reduction

And for determining the electron movement in reduction and oxidation we use: <b>Oil Rig</b>

<b>Oil</b> - oxidation/loss

and

<b>Rig</b> - reduction/gain


Lol, just some more of those silly abbreviations. I have found them to be very effective in helping you to remember these things. :)
 
P

pLuvia

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Sammy Man said:
Hey guys

I was just wondering how to determine the Anode and the Cathode in a galvanic cell?
I know that oxidation occurs at the Anode, and Reduction occurs at the Cathode, but how do i tell them apart?

Your help is much appreciated, cheers.
The lower the metal on the Standard reduction table the more likely it will be the cathode and the higher up the metal is the more likely it will be oxidised
 

alcalder

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Cathode rays (which are moving electrons) come from the Cathode and pass to the Anode (I know, that's Physics, but let me get to my point :D). THUS the cathode is the negative electrode and the anode is the positive electrode. This is OUTSIDE THE POWER SOURCE.

The Cathode will be connected to the negative side of the power supply and the Anode to the positive side of the power supply.

Keeping this in mind, always connect black leads to the negative side and red to the positive side and you will not get yourself confused when everything is hooked up and wires cross and tangle.

NOTE: Use yellow leads when using AC.

Now, if you are MAKING the battery in electro-chemistry then you are looking INSIDE THE POWER SOURCE. So the cathode and anode are reversed and you are adding potential to electrons. So, Cathodes are pulling electrons FROM the anode in order to feed them into the external circuit.

I hope that helps.
 
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