V.13 Electroplating

p.243-246

Electroplating

•An electrolytic process in which a metal is reduced or “plated out” at a cathode

•The cathode is made out of the material which will receive the metal plating

•Electroplating solution contains ions of the metal which is to be “plated” onto the cathode

•An inert electrode can be used as an anode, or the same metal which is to be “plated out”

p. 244: 73

•Electroplate iron with chromium.

Electrorefining

•Process of purifying a metal by electrolysis

•Diagram p. 245•Zn & Pb will oxidize first, but most of the electrode is copper so then it will oxidize

•Anode:Cu(impure)Cu2++2e- E°=-0.34V

•Cathode:Cu2++2e- Cu(pure) =0.34V

Cu(impure)+Cu2+Cu2++Cu(pure) =0.0V

•Any bits of Ag, Au, Pt are spectators and will drop off Cu and form sludge

•P. 246:78