galvanic vs electrolytic

[eravin99]

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can someone please explain how t ofind the EMF? everywhere i read, it says something slightly different. how can you tell which one to switch? i just thought you always switch the more neg number!

thanks in advance :0)

 

[TimeforDAT]

delta G = -nFE

you need to consider the half reactions given along with the overall reaction. Do the half reactions follow the given overall equation. If you need to switch a half reaction, then you need to switch the sign of that respective reduction potential. Now you add the two reduction potentials given, and that is your E. Now you plug that into the delta G equation

 

[jackbauer!]

galvanic cells are spontaneous; therefore have a neg. delta G and a pos. E cell. to find the EMF, subtract the smaller reduction potential from the larger one to ensure that you end up with a positive E cell.

electrolytic cells are non-spontaneous; therefore, have a pos. delta D and a neg. E cell. to find the EMF, subtract the larger reduction potential from the smaller one to ensure that you end up with a positive E cell.

some other information... oxidation (loss of electrons) always occurs at the anode and reduction (gain of electrons) always occurs at the cathode. however, electrons flow from anode to cathode in a galvanic cell and in the opposite direction in electrolytic cells.

hope that helps. jB!🙂

 

[zackscoot]

galvanic cells are spontaneous; therefore have a neg. delta G and a pos. E cell. to find the EMF, subtract the smaller reduction potential from the larger one to ensure that you end up with a positive E cell.

electrolytic cells are non-spontaneous; therefore, have a pos. delta D and a neg. E cell. to find the EMF, subtract the larger reduction potential from the smaller one to ensure that you end up with a positive E cell.

some other information... oxidation (loss of electrons) always occurs at the anode and reduction (gain of electrons) always occurs at the cathode. however, electrons flow from anode to cathode in a galvanic cell and in the opposite direction in electrolytic cells.

hope that helps. jB!🙂

In addition to that, some else that is important and you MUST know. in galvanic cells, anode is negative and cathode is positive. In electrolytic cells, anode is position and cathode is negative!!!

 

[AaBbZz]

Problems where they give an equation and a list of reduction potentials just find which element is being Reduces (GER-gain of electrons) and which is being ozidized (Loss of electrons)

The list of half reactions is always Reduction potentials-what is being reduced so find that element and then look for the oxidizing element and flip that E value (remember the oxidizing potential is the exact opposite than the reducution potential)

Now add the two together. If E is positive then it is a Galvanic Cell (spontaneous) If E is negative it is an Electrolytic cell, nonspontaneous.