How is a galvanic cell different from an electrolytic cell?

[whatwhy]

---

Members do not see this ad.

I always get questions regarding this wrong since I think too much into it. I guess I'm just confused about how a battery is used to power that cell and what it means for the cell. Thanks.

 

[1TB4RKSB4CK]

TBR has a great explanation for this. Either that, or just go look it up on the internet https://www.google.com/search?q=gal...US504US504&espv=210&es_sm=91&biw=1181&bih=658

 

[brood910]

I will just write these things down to do a quick review for myself.

Galvanic: anode is negative + cathode is positive, produce electricity, exothermic, spontaneous (-G, +emf),
Electrolytic: exactly the opposite.

 

[DrMula]

I always get questions regarding this wrong since I think too much into it. I guess I'm just confused about how a battery is used to power that cell and what it means for the cell. Thanks.

They say teaching something is a good way to learn it yourself...so here goes nothing.

Always remember that the cathode is where reduction occurs and the anode is where oxidation occurs...(this is common for any type of cell!)

Okay now in a galvanic cell, the electrons from the anode (-) travel to the cathode (+). This is spontaneous (electrons negatively charged moving towards a + charge)--this is why a galvanic cell doesn't need an external power source to drive the reaction.

In an electrolytic cell the cathode IS STILL where reduction occurs and the anode IS STILL where oxidation occurs, however, the species at the cathode will be the one with the lower reduction potential (or higher oxidation potential) and the species at the anode will be the one with the lower oxidation potential (or higher reduction potential). So in other words, the species at the anode does not want to get oxidized and the species at the cathode doesn't want to get reduced. This is why a galvanic cell needs an external power source, because you are forcing a non-spontaneous reaction to occur.

So, for example oxygen naturally likes to get reduced and get a -2 charge while calcium likes to get oxidized and become +2 charged. In the galvanic cell oxygen would naturally be at the cathode (where reduction occurs) and calcium would naturally be at the anode (where oxidation occurs); but in an electrolytic cell, oxygen would be forced to be at the anode (where oxidation occurs--remember oxygen would rather be reduced) and calcium would be forced to the cathode (where reduction occurs--remember calcium would reather be oxidized). Of course this reaction would need an external power source.

(PS don't forget about salt bridges--they play an important role too!)

Hope this help, but there's no substitute for digging deep yourself!
Good Luck!

 

[SN2ed]

Thread closed. These types of questions belong in the MCAT Study Q&A.