1. Voltaic Cells
Aim: To identify the components and explain the functions of an electrochemical (voltaic) cell.

2. What is a Voltaic Cell?
Voltaic cell (aka galvanic Cell, Electrochemical Cell) an electrochemical
cell where chemical energy is converted to electrical energy spontaneously.
The energy produced by an electrochemical cell is measured in volts

3. Parts of a Voltaic Cell ·Wire and voltmeter ·Two metal electrodes
·TWO half-cells
·Wire and voltmeter
·Two metal electrodes
·Salt bridge
·Two salt solutions containing metal ions of the electrodes.

4. Use Table J to determine which metal electrode is more active.
The MORE active metal is oxidized and will be the anode. Zn Cu

5. Voltaic Cell
Electrodes:
Anode: -
Cathode: +

7. CuCl2(aq)
ZnCl2(aq)
Copper
( Cu0)
Zinc
( Zn0)
Cu2+
Cu0
Cl -
Zn0
Zn2+

8. How does a Voltaic Cell work?
·The wire connects the electrodes and the salt bridge connects the ionic solutions to complete the circuit. The salt bridge promotes the flow of anions to prevent the buildup of charge in either half-cell.
·Oxidation occurs at the ANODE and as electrons are lost, metal cations form and dissolve into the solution, decreasing the anodes mass.
·The lost electrons from the metal of the anode and attract to the positively charged cathode and flow through the wire to it.
·The electron build up in the metal cathode causes the positive metal cation reduction at the CATHODE and as the cations are reduced they plate onto the cathode, increasing the cathode’s mass.
·The flow of electrons and ions through the completed circuit generates electricity from the chemical reaction. VOLTAIC CELLS ARE SPONTANEOUS.

9. Voltaic Cell Animations

10. What happens in the cell?
Copper ( Cu0)
Zinc
( Zn0)
Cu0
Cu0
Cu0
Zn0
Zn0
Cu2+
Cu0
Zn0
Cu0
Cu2+
Zn0
Cu0
Cu2+
Cu2+
Zn0
Zn0
Cu2+
Cu2+
Zn2+
Cl -
Cu0
Cl -
Zn0
Cu2+
Cu2+
Cu2+
Cl -
Cl -
CuCl2(aq)
ZnCl2(aq)
1) Using Table J, determine which electrode is the anode and which is the cathode. Indicate the direction the electrons flow (current).
a. Anode:
b. Cathode:
c. Direction of electron flow:
2) What occurs at the anode?
3) What happens to the electrons lost by the zinc electrode during oxidation?
4) Write the half reaction that occurs at the anode.
5) What happens to the mass of the anode? (hint: "OIL RIG")

11. What happens in the cell?
Copper ( Cu0)
Zinc
( Zn0)
Cu0
Cu0
Cu0
Zn0
Cu2+
Zn0
Cu0
Zn0
Cu0
Cu0
Cu2+
Zn0
Cu0
Cu2+
Cu2+
Zn0
Cu2+
Zn2+
Cu0
Cu2+
Zn0
Cl -
Cl -
Cl -
Cl -
Cu2+
Cu2+
Cu2+
CuCl2(aq)
ZnCl2(aq)
6) What occurs at the cathode?
7) What is reduced at the cathode?
8) Write the half reaction that occurs at the cathode.
9) What happens to the mass of the cathode?
10) How does the concentration of the Cu+2 ions change? How does the concentration of the Zn+2 ions change?

12. Example 1: Mg Na
NaCl(aq)
MgCl2(aq)
Write the oxidation and reduction half reactions for the cell.
ox 1/2:
red 1/2:
2) What happens to the mass of both electrodes?
Mg(s) mass ___________
Na(s) mass ___________
3) What happens to the concentration of each of the following ions?
Mg2+ concentration______________
Na1+ concentration ______________
4) Which way do the electrons flow?

13. Fe K
FeCl3 (aq)
KCl (aq)
Example 2:
Write the oxidation and reduction half reactions for the cell.
ox 1/2:
red 1/2:
2) What happens to the mass of both electrodes?
Fe(s) mass ___________
K (s) mass ___________
3) What happens to the concentration of each of the following ions?
Fe+3 concentration______________
K+1 concentration ______________
4) Which way do the electrons flow?