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### Determining the cathode/anode

Posted: Fri Mar 06, 2020 9:48 pm
How would you determine the cathode or anode of a cell by only knowing the E value of the half reactions (assuming the you don't know which electrode is being oxidized or which is being reduced)?

### Re: Determining the cathode/anode

Posted: Fri Mar 06, 2020 11:36 pm
the anode is the one with the most negative potential

### Re: Determining the cathode/anode

Posted: Sat Mar 07, 2020 12:31 am
You can use the equation Ecell = Eright - Eleft to deduce the cathode and anode. Eright would be the cathode and Eleft would be the anode.

### Re: Determining the cathode/anode

Posted: Sat Mar 07, 2020 1:09 am
The total Ecell should always be positive (unless the cell was powered by some non-spontaneous energy source). So if you have the standard E values for the half reactions (both in reduction form) you should flip the one that makes the total Ecell the most positive. The flipped half reaction is the oxidation reaction and it would occur at the anode.

### Re: Determining the cathode/anode

Posted: Sat Mar 07, 2020 10:37 am
Since the half reactions are usually given to us as reductions, the standard potential of the cathode should be greater than the anode.
This is because $E^{\circ}$ is the standard potential of the half reaction. The greater it is, the more likely it is that the reaction will occur. We are always given reduction half reactions, and we know that reduction occurs at the cathode. Therefore, the reaction with the highest potential occurs at the cathode.
If the half reactions are oxidation reactions, then E represents the oxidation potential and the reaction with the greater number occurs at the anode.

### Re: Determining the cathode/anode

Posted: Sat Mar 07, 2020 10:58 am
The more negative cell potential has the most powerful reducing power and is therefore the anode.

### Re: Determining the cathode/anode

Posted: Sat Mar 07, 2020 11:19 pm
Samuel G Rivera - Discussion 4I wrote:How would you determine the cathode or anode of a cell by only knowing the E value of the half reactions (assuming the you don't know which electrode is being oxidized or which is being reduced)?

To determine which is the anode, and which is the cathode, you look at the standard reaction potentials and whichever is most positive, that is the cathode; the other is the anode. In a concentration cell, the larger concentration is the cathode.

### Re: Determining the cathode/anode

Posted: Sun Mar 08, 2020 12:36 am
Use Ecell = Ecathode - Eanode... in a galvanic cell, make sure that Ecell is positive, so the cathode needs to be more positive and the anode more negative.

### Re: Determining the cathode/anode

Posted: Sun Mar 08, 2020 12:57 am
The most negatively reduced standard cell potential occurs at the cathode and the most positive standard cell potential occurs at the anode.

### Re: Determining the cathode/anode

Posted: Sun Mar 08, 2020 6:32 pm
the anode is the more negative cell potential and the cathode is the more positive one