Electrochemistry

Electrolysis

Complete Galvanic Cell

Electrolysis-requires energyElectrolysis-requires energyElectrolysis with Active ElectrodesElectrolysis with Active Electrodes

Electrochemical cells

galvanic cell – spontaneous chemical reaction produces an electric current

Electrolytic cell – electric current drives a nonspontaneous reaction

Redox reactions involve a transfer of electrons.

Zn(s) + CuCl2(aq) ZnCl2(aq) + Cu(s)

Zn(s) + Cu2+(aq) Zn2+(aq) + Cu(s)

Galvanic vs Electrolytic

Electrolysis• Process that involves forcing a current through a

cell to produce a chemical change for which the cell potential is negative.

• Electrolytic cells

• Electron flow is reversed from galvanic

• Anode and cathode are reversed from galvanic

Electroplating

• How much chemical change occurs with the flow of a given current for a specified time?

• Current is measured in amperes (A).

1 A = 1 C/s

Another Question For You• What mass of Cu is plated out when a current of

10.0 A is passed for 30.0 min through a solution containing Cu2+?

Cu2+ + 2e- Cu

30.0 min (60 s / 1 min) = 1800 s

1800 s (10.0 C/ 1 s) = 18,000 C

18,000 C (1 mol e- / 96,485 C) = 0.187 mol e-

0.187mol e- (1mol Cu / 2mol e-) = 0.094mol Cu

0.094 mol Cu (63.546 g /1 mol Cu) = 5.94 g Cu

multimeter

ring stand

clamp

inverted buret