| MadSci Network: Chemistry |
|
Hello, I am in an AP chemistry class and right now we are studying
electrolytes. I know that dissociated ions are what make these solutions
conductive, but I was wondering what the mechanism of conduction is. How do
the electrons acually move in to and out of the ions? I would intuitively
think that ions would be worse conductors since they have higher ionization
energies than the unionized molecule. My teach is also stumped on this, any
insight woul help a lot. Thank you very much.
You're on the wrong track here. Electrolytes work because the ions themselves are the medium for electricity: electricity is carried by moving electrical charges and any charged "particle" will do! For example, it's legitimate to describe electricity as moving holes, positively-charged places where electrons used to be, just as if you described traffic flow in terms of the movement of open spaces between cars. Free electrons don't flow through aqueous solutions. Instead, ions move through the solution. This makes electrical conduction through solutions rather slow. An electrical current, which is flowing electrons, can be completed through an electrolyte solution not because electrons move through the solution but because positive ions stream over to the side where electrons are building up and negative ions stream over to the side with an electron deficiency. Eventually enough electrical potential builds up so that you actually have some chemistry occurring in the electrolyte solution... that's how you get water electrolysis. At the anode (where electrons are deficient) water breaks down to H+ and O2; at the cathode (where electrons are in excess) water breaks down into H2 and OH-.
|
Try the links in the MadSci Library for more information on Chemistry.