Friday, October 1, 2010

REDOX -Lesson summary.

Monday, September 13, 2010

REDOX - electrolysis as aqueous of molten?

Only copper ions, silver ions and gold ions can undergo electrolysis as an aqueous solution.
Every other metal ion needs to be in its molten state.

Because in an aqueous solution there is also H+ and OH- ions present H2O --> H+ + OH-
and so the H+ ions compete for the cathode with the metals ions.
Because all metals except Cu, Ag, Au are more reactive than H, the H+ ions will be reduced to H2 before the others.
(remember the more reactive the metal is the more stable the metal ions is, and so the harder it is to reduce.)

REDOX - electrolysis

This is used to make a chemical take back electrons when it rather wouldn't.
Cu + Cl2 --> 2CuCl2 This is spontaneous. It is a REDOX.

Cu --> Cu2+ + 2e- (LEO-oxidation)
Cl2 + 2e --> 2Cl- (GER- reduction)


CuCl2 --> Cu + Cl2 is not spontaneous but can be achieved via electrolysis.