Electron-volt in chemistry

pwood

Hi all,
My instructor in my college chemistry class continually refers to cell potentials (as in battery cell potentials) in units of electron-volts. Is there any case in physics or chemistry where this is correct? My understanding is that an electron-volt is generally a unit of energy, but I didn't think it was correct to use it for electric potential, cell or not.
Thanks,
PWood

Woopydalan

Electron volts are used when the energy involved is extremely small.

1 eV = 1.6 x 10^-19 J...so when you are talking about very small amounts of energy, it is more convenient to express the energy as an eV than a joule.

pwood

Hi Woopydalan,

I appreciate your post, but I already stated that I knew that it was a unit of energy. What I am asking is: are there any uses of the electron-volt that interpret it as a unit of electric potential? That is how my chemistry instructor uses it, I believe incorrectly.

I am aware that it is used in some fields as a unit of mass, momentum, and distance. I am in doubt that it is ever used as a unit of electric potential.

So, that is the question: is it ever (correctly) interpreted as a unit of electric potential?

AGNuke

Two cases : Either the professor is taking off on wrong foot (happens all the time) or he actually may mean another thing.

Case 1: Just delete the term electron in your mind. You're more than happy person.

Case 2: 1 Electron volt is the energy of an electron when it is accelerated by the potential difference of 1 Volt. Since in electrochemistry, the cells (or Redox couple) we make have some electrons transfer from Anode to Cathode, accompanied by the generation of Potential, "Maybe" he may had mixed those two things as one.

Your best bet is still to ask him loud and clear. And if you are afraid, ask him in a form of a text book question, in which the answer is in form of Volts.

chemisttree

He's probably expressing the potential as E^o Volts... which is a standard electrode (the "E^o" part) in units of volts.