cathode labeling convention

[Oh_Gee]

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from GS-9

i thought by convention cathodes are (-) charged because cations go toward them. also electrons flow toward them so shouldn't a cathode be (-) charged ?

 

[justadream]

Charged Capacitor:
Cathode: Negative
Anode: Positive

Discharging Battery:
Cathode: Positive
Anode: Negative

 

[MedHopeful20134]

Think of it like this:
Positive cathode attracts electrons (which are negatively charged) towards them, a spontaneous process in galvanic cell.

 

[Oh_Gee]

Charged Capacitor:
Cathode: Negative
Anode: Positive

Discharging Battery:
Cathode: Positive
Anode: Negative

which one of these is a voltaic cell?

Think of it like this:
Positive cathode attracts electrons (which are negatively charged) towards them, a spontaneous process in galvanic cell.

isn't the cathode negatively charged because the anode sends electrons to it? (meaning the anode becomes + charged since it is losing electrons?)

 

[justadream]

@Oh_Gee

That would be a discharging battery.

 

[3655]

which one of these is a voltaic cell?


isn't the cathode negatively charged because the anode sends electrons to it? (meaning the anode becomes + charged since it is losing electrons?)

Well the cathode is positively charged because the cathode in a voltaic cell is positive which attracts the electrons coming from the anode making the reaction a spontaneous and favorable one.

 

[Oh_Gee]

so is this correct? also where should i put gel electrophoresis set up and electroplating(electrolytic example i think)


Galvanic (voltaic)- negative delta g, spontaneous, postive emf. electrons goes left to right(anode to cathode). to increase voltage, increase conc of ions in cathode or decrease conc of ions in anode. electrons go toward the cathode which is + charged . anode is - charged (why though???)
anode Zn>Zn2+ + 2e-
cathode Cu2+ + 2e- > Cu
examples: discharging battery

electrolytic- non spontaneous, a voltage source is added to make electrons go from cathode to anode. the applied voltage must exceed the natural voltage. cathode is - charged because the metal is being oxidized. anode is + charged because the ion is getting reduced meaning that it is losing its + charge
anode Cu> Cu2+ + 2e-
cathode Zn2+ + 2e->Zn
examples: charging battery

 

[justadream]

@Oh_Gee

In all cells (yes, that means both galvanic and electrolytic), electrons go from anode to cathode. Oxidation occurs at anode. Reduction occurs at cathode.

 

[Oh_Gee]

@Oh_Gee

In all cells (yes, that means both galvanic and electrolytic), electrons go from anode to cathode. Oxidation occurs at anode. Reduction occurs at cathode.

can you explain why the anode(sends electrons away) is negatively charged in a galvanic cell?
is it because it's repelling these electrons

 

[justadream]

can you explain why the anode(sends electrons away) is negatively charged in a galvanic cell?
is it because it's repelling these electrons

I think it's just a convention.

To quote @BerkReviewTeach

"For a battery in a circuit (according to physics convention), we are told that the anode must be negative, because current is flowing to it. We are likewise told the cathode must be positive, because current is flowing from it. The reality is that it is a chemical reaction that generates the emf and there is not actual charge on either electrode. But by convention in physics, the cathode terminal of a battery is assigned a (+) and the anode terminal of a battery is assigned a (-)."

http://forums.studentdoctor.net/threads/why-is-an-anode-negatively-charged.712243/