HELP!! can anyone explain the galvanic cell?? (1 Viewer)

[mathock]

I'm stressing, our teacher has that many mnemonics going at once, from OIL RIG to LEO GER and everything in between, I'm so confused about the galvanic cell and how it works can anyone help please??

Chem tomorrow!! argh!!

 

[Paroissien]

OIL RIG: Oxidation Is Loss of electrons and Reduction Is Gain of electrons
RED CAT and AN OX: Reduction at cathode and oxidation at anode
Never heard of LEO GER: but my guess is that loss electrons oxidation and gain electrons reduction

And do HSC papers to know the knd of question they'll ask. They won't ask you to describe how a galvanic cells works so don't stress too much.

 

[Tommy_Lamp]

A Galvanic Cell is fairly simple and the only Mnemonics you need are OIL RIG (Oxidation Is Loss, Reduction Is Gain (of electrons)) and a picture of a red cat with a positive butthole (obscene but useful).
Basic explanation: Two different metals are placed in separate beakers with an electrolyte and a salt bridge (a diagram is in every book). On your standard potentials table, every equation as written is reduction and hence the cathode and positive (hence the red cat with the positive butthole)
The more reactive metal (read off the standard potentials table) will be reversed, becoming the anode meaning that is where oxidation occurs. From the mnemonic OIL RIG, it is clear that the Cathode, being Reduction, will gain electrons and the Anode, being oxidation, will lose electrons.

Hope that helps.

 

[lucyinthehole]

so, wait. let me just check. oxidation ALWAYS occurs at the anode, and reduction ALWAYS occurs at the cathode, but whether they're positive or negative changes between an electrolytic cell and a galvanic cell right?

 

[Doogsy]

I first write down the two half cell reactions from the reduction potentials, and flip one of them so the sum of the E values is the greatest +ive answer.
eg Pb and Ag

Pb2+ + 2e- -> Pb E=0.8
Ag+ + e- -> Ag E=-0.14
now we flip Ag because we want the highest positve E value
Ag -> Ag+ + e- E=0.14
now Pb is reduced (cause its straight of the reduction table) and we flipped Ag so it is oxidised.

ANOX REDCAT we know AG is anode and Pb is cathode. (anode is oxidation, reduction is cathode)
from there 0.8 + 0.14 = total E = 0.94

thats how i do it anyway.

 

[Tommy_Lamp]

Yes. In an electrolytic cell the charges reverse, hence the Anode becomes positive and the Cathode becomes negative. This is due to the different direction of current.

 

[Doogsy]

cathode is negative in electrolytic. I remeber that and it works.

 

[Paroissien]

Correct me if I'm wrong but electrolytic cells aren't even in the core topics

 

[xeriphic]

galavanic cell is basically the action of redox reactions which generates an electric current, where the external circuit is for electron transfer and the internal circuit for the transfer of ions

more reactive metal will displace the lesser reactive metal (ie. transfer electron to the less reactive)

oxidation is loss of electrons, at the anode (-) electrode (stronger metal)

reduction is a gain of electrons, at the cathode (+) electrode (weaker metal)

in an experiment through observations, anode will become thinner, while the cathode gets bigger

 

[lucyinthehole]

thanks doogsy and tommy_lamp

 

[Tommy_Lamp]

Yeah they are only in Shipwrecks, but when your doing that elective it gets hard to separate Galvanic and Electrolytic Cells when discussing one of them

 

[xeriphic]

Correct me if I'm wrong but electrolytic cells aren't even in the core topics

it isn't though chem context 2 placed in productions section

 

[Tommy_Lamp]

It used to be in the core but with the continuous dumbing down of the syllabus, it isn't anymore.

 

[Paroissien]

Jeez they have removed a lot of stuff. Not that I'm really complaining... but they must not think much of our abilities

 

[lucyinthehole]

and good on them for underestimating us

if they didn't, i'd be even more screwed.

 

[xeriphic]

I'm not complaining =p lol

 

[mathock]

haha thanks you guys, yas are all legends... i think i might live to see another day cheers

 

[mathock]

by the way, LEO GER is "Loss of Electrons - Oxidation Gain of Electron - Reduction"

 

[Tommy_Lamp]

Ech thats a nasty mnemonic, I just prefer OIL RIG

 

[Paroissien]

I don't bother with a mnemonic for that one. But I do like RED CAT and AN OX