Electrochemical Cells:

1

• Electrochemical Cells

(ie Batteries or Galvanic Cells)

• Redox reactions that take place in such a way
  that electrical energy (or voltage) is produced,
  instead of energy being released as heat (as in
  the following)

eg Place Zn(s) in Cu(NO3)2(aq)
Cu(s) deposits while Zn2 dissolves into solution.
Cu(NO3)2(aq) Zn(s) ? Cu(s) Zn(NO3)2(aq)
Net Ionic Cu2(aq) Zn(s) ? Cu(s)
Zn2(aq)

• In this example energy is released as heat.

• We need to modify this system to produce
  electrical energy rather than heat.

2
eg An electrochemical cell using Zn and Cu.
e-
NO3-
K
CATHODE
ANODE
Zn(s) ? Zn2 2e-
Cu2 2e- ? Cu(s)
Oxidation at Anode
Reduction at Cathode
3
Practice
Sketch the following electrochemical cells

• Cs, Mg

• Zn, Ca

• Cu, Mn

• Sn, Cr

• Al, Pb

• Use nitrates of corresponding metals

• Label anode, cathode, salt bridge, chemicals,
  and direction of electron and ion flow.

• Include the half-reaction for each half cell.

• Predict which cell will have the highest voltage.