Batteries

[Sammy1024]

Do electrons go from cathode to anode in a recharging battery? I've seen some passages where electrons are going cathode to anode.

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[sps27]

Do electrons go from cathode to anode in a recharging battery? I've seen some passages where electrons are going cathode to anode.

The flow of electrons in the outer circuit during re-charging will still be from anode to cathode, while inside the cell, the flow of electrons will be from cathode to anode. Re-charging is like an electrolytic cell. The anode of the external battery is connected to the cathode which makes the cathode as -ve, and the cathode of the external circuit is connected to the anode, which makes anode as +ve. So essentially when electrons flow from anode to cathode in external circuit, inside the cell they flow from cathode to anode. I like to think of galvanic cell as charging, and electrolytic cell as re-charging. Let me know if I am wrong.

 

[Blueprint MCAT Tutor]

Interesting question! My reply here (scroll to the bottom):

http://forums.studentdoctor.net/threads/specific-science-questions.1053558/

 

[sps27]

Interesting question! My reply here (scroll to the bottom):

http://forums.studentdoctor.net/threads/specific-science-questions.1053558/

Thanks for the link. There is a lot of stuff in there -- about things that cause confusion. I appreciate it.

 

[Sammy1024]

Wait, cathode is positive and anode is negative, so wouldn't electrons want to anode to cathode? Why do they decide to "switch" directions?

 

[Blueprint MCAT Tutor]

Wait, cathode is positive and anode is negative, so wouldn't electrons want to anode to cathode? Why do they decide to "switch" directions?

Seriously, just let that go man.

You're walking into a world of heartache and pain trying to wrap your head around the whole "which is positive and negative and why". It's a minefield. It's like trying to talk to my Uncle Donald about politics at Thanksgiving dinner after he's housed a dozen beers. All you're going to do is get angry and confused.

Just memorize: GAIN. Galvanic Anode Is Negative. That'll get you through any MCAT questions that require you to know which is pos and neg.

 

[Sammy1024]

Hahaha. So Galvanic Anode is Negative, and so electrons go from Anode to Cathode?

 

[Blueprint MCAT Tutor]

Hahaha. So Galvanic Anode is Negative, and so electrons go from Anode to Cathode?

Yup.

By definition: RED CAT, AN OX

So if reduction is taking place at the cathode, you're gonna need some electrons to reduce that stuff.

So electrons flow to the cathode.

Always, always, always.