Chemistry / Unit 11 Chem 2156 short lesson, about 20 seconds
Twin: The Anode/Cathode Charge-Sign Reversal
Captions available
The idea
A galvanic cell's anode is negative and cathode positive, but an electrolytic cell's anode is positive and cathode negative, since an external source now forces electron flow.
In practice
A galvanic zinc anode loses electrons willingly, reading negative; an electrolytic anode is forced to give up electrons, reading positive.
Where people slip
Carrying galvanic signs onto an electrolytic cell reverses both electrodes, though "anode oxidizes" still holds.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Chemistry