## Identifying Which Half-Reaction to Reverse

Yusrah Ishtiaq 1E
Posts: 21
Joined: Fri Sep 25, 2015 3:00 am

### Identifying Which Half-Reaction to Reverse

In lecture today, Professor Lavelle said that you reverse the half-reaction that, after you reverse, will cause you to get a positive value of voltage. So, does this mean the voltage always has to end up as a positive value?

Samantha Miceli 3J
Posts: 20
Joined: Fri Sep 25, 2015 3:00 am

### Re: Identifying Which Half-Reaction to Reverse

In these problems you want to get a positive voltage. From lecture today, Lavelle mentioned that if there is a negative voltage, then the reaction is not favorable.

Reine Nakamura 1C
Posts: 38
Joined: Fri Sep 25, 2015 3:00 am

### Re: Identifying Which Half-Reaction to Reverse

I think that statement mainly applies to the redox reactions having to do with batteries, since batteries never have a negative voltage. However, in the example on page 52 in the course reader, the $E^{\circ}$ is -0.54 V, showing that negative cell potentials are possible in certain cases.

Shaye Busse 3B
Posts: 20
Joined: Fri Sep 25, 2015 3:00 am

### Re: Identifying Which Half-Reaction to Reverse

Of course a negative net voltage is possible for a galvanic cell, it simply means so many volts of electricity need to be put into the system in order to have the reaction proceed in the set direction.