18.8 Electrolysis 2 Types of electrochemistry 1.Battery or Voltaic Cell – Purpose? 2.Electrolysis - forces a current through a cell to produce a chemical change that would not otherwise occur.

Battery – voltaic cell Pb + H 2 SO 4  PbSO 4 + 2H + + 2e - Anode PbO 2 + H 2 SO 4 + 2e - + 2H +  PbSO 4 + 2H 2 O Cathode

Electrolysis of salt water Na +, Cl -, and H 2 0 are present Possible oxidation reactions. 2Cl -  Cl 2 + 2e - 2H 2 O  O 2 + 4H + + 4e - Possible reduction reactions Na + + e -  Na 2e - + 2H 2 O  H 2 + 2OH -

Electrolysis A process where electrical energy is used to produce a chemical change. Involves forcing a current through a cell to produce a change that would otherwise not occur. Electrolysis of water produces hydrogen gas and oxygen gas. Electrolysis is used to recharge lead storage batteries.

Electroplating A thin layer of one metal is deposited onto another. There is normally only one solution that supplies the metal needed. + - Cu 2+ FeCu Cu  Cu e - Cu e -  Cu