Why do Cathodes carry a positive charge and Anodes carry a negative charge in galvanic cells, but in electrolytic cells, Cathodes have a negative charge and Anodes have a positive charge? I’m a grade 12 chemistry student and I’m having trouble understanding this concept. Could someone please explain the rationale behind this apparent reversal of charges in the two types of cells?
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I think of it in terms of anode and cathode define the direction electrons are currently flowing (regardless of which direction is thermodynamically favored) while the charges define the direction that electron flow would be spontaneous or TDF (based on the relative reduction potentials of the two half cells). In essence, the charges are defined based on what two half cells are put together, and electrons are flowing in the spontaneous direction if they are flowing from the negative to the positive electrode.
However, I define the direction I want electrons to flow. If I want them to flow from negative to positive (negative electrode is the anode and positive is the cathode), then I’ve made a galvanic cell and the electrons will flow the desired direction all on their own. However, if I want the elections to flow from positive to negative (positive is the anode and negative is the cathode), then I’ve made an electrolytic cell and I’ll have to hook up my cell to an outside power source to force the electrons to flow the direction I want them to.
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