CHEMISTRY COMMUNITY

How do you tell which equation is the anode and which is the cathode ?

I don't know the question you're referring to in full, but in general, oxidation occurs at the anode and reduction occurs at the cathode. When looking at a reaction, identify the two half reactions to see which one is being oxidized (losing electrons) and which one is being reduced (gaining electrons). Hope that helps.

If you use the acronyms OIL RIG (oxidation is losing (e-), reduction is gaining) and An Ox/Red Cat (anode=oxidation, cathode=reduction), you can easily figure out which molecules are gaining/losing electrons and pair them up with their appropriate electrode.

In the problem I am referring to, there is an equation given where it can go either way. So it is not as easy as looking at which species is oxidized or reduced( or which species is losing or gaining electrons).

What I have figured out is that the anode usually has the lower E of cell? Is that a good way of figuring out which is the anode and which is the cathode or is that not always accurate?

The more negative E is the one that is reduced. So, yes that is an accurate way to determine which side.

For 14.13c why is the Cl- put before the Cl2 when they are the ones being reduced. Shouldn't Cl be put in front of the Cl- or does the phase matter?