Galvani observed frog leg twitching from current flowing through electrolytes, inspiring Volta to invent the first battery by connecting multiple cells producing a consistent current. Cells contain liquid electrolytes and electrodes, with voltaic cells producing electricity spontaneously via redox reactions and electrolytic cells using electricity to force redox reactions. Voltaic cells, also called galvanic cells, use a salt bridge or porous disk to allow charge balance as ions move between electrodes undergoing redox. Cell properties include potential difference as energy per unit charge and current as charge flow rate, with batteries connecting galvanic cells in series to add potentials. Secondary cells can recharge through added electricity input.

1. 14.1 Cells and Batteries

2. Origins of the Cell
• Galvani (late 1700’s) observed a frog’s leg
twitch when exposed to a current
• Volta (early 1800’s) realized it was due to
current flowing through electrolytes in body
• Volta invented the first battery by
connecting multiple electric cells together
• Based on spontaneous redox rxtn’s it was
able to produce a consistent current

3. +
+
+
–
–
–
Cell design
• “Cells” are containers of liquid with electrodes:
• In “voltaic cells”, electricity is produced
spontaneously from a redox reaction
• In “electrolytic cells”, electricity is used to force
chemicals to undergo a redox reaction
Source or use
of electricity
Molten or
aqueous
chemicals
Cell Electrode

4. Voltaic Cell
• also referred to as a “galvanic cell”
• salt bridge or porous disk(cup) used to allow for
unrelated ions to move to allow for balance of charge

5. Cell Properties
- driving force on electron to move them through the
wire
• electric potential difference is the energy difference
per unit charge
• depends on type of electrodes and electrolytes used in
cells
• electric current is rate of flow of charge in a circuit
• power is the rate at which electrical energy is
produced

6. Cell Quantities
Quantity Symbol Meter Units
Charge Q C (coulombs)
Current I ammeter A (ampere)
Potential
difference
V voltmeter V (volt)
Power P W (watt)
Energy
density
J/kg

7. Secondary Cells & Batteries
 a battery is a group of galvanic cells
connected in series
 the potentials of the individual cells add
to give the total battery potential
 secondary cells can be recharged by
adding electricity

8. Figure 7 One of the Cells in a 12-V Lead Storage Battery (LSM 14.1C)

9. Figure 6 A Common Dry Cell Battery (LSM 14.1C)

10. Fuel Cells
. . . voltaic cells where the reactants are
continuously supplied.
2H2(g) + O2(g)  2H2O(l)
anode: 2H2 + 4OH  4H2O + 4e
cathode: 4e + O2 + 2H2O  4OH

11. Figure 8 Schematic of the Hydrogen-Oxygen Fuel Cell (LSM 14.1C)

12. Homework
Textbook p. 614 #1-5
Textbook p. 619 #10-15
LSM 14.1 B,C,D