Electrochemistry involves the flow of electrons between different metals. Luigi Galvani discovered that frog legs moved when touched with different metals, showing the connection between electricity and biology. Alessandro Volta found that two different metals in contact could generate electricity through the transfer of electrons from one metal to the other. He created the voltaic pile, consisting of alternating zinc and copper discs separated by cardboard soaked in brine, which produced a steady current. Later improvements included the Daniel cell and crowfoot cell, which used zinc and copper electrodes in a liquid electrolyte and were used for telegraph communications until the 1950s.

1. electrochemistry
Volts Amps and Coulombs!

2. Luigi Galvani
• Discovered that frog’s leg moved when touched by
something with “static” electricity.
• Animals systems of muscles are controlled and
activated by electricity
• 1780
• A galvanic cell is a
different name for a battery.
FRANKENSTEIN written after
Author Mary Shelley heard about
Galvani’s work.

3. Allessandro Volta
• Found that two different metals together can
“exchange electrons” where one gains and the
other loses them. REDOX.
• Touch a frog’s leg with two different metallic
probes and the leg “jumps”
• OIL RIG
• LEO GER
• Has the “volt” named after him

4. Voltaic Pile
Zinc “LOSES” electrons OIL
Copper+2 gains electrons RIG
This “flow” of electrons between the
two is called electricity

5. Voltaic Pile
Zinc “LOSES” electrons OIL
Copper+2 gains electrons RIG
This “flow” of electrons between the
two is called electricity
Electrons come
out of the
battery here

6. Daniel Cell
• A variation of Volta’s “pile” that was easier to
use and more portable.
• Still used Zn and Cu as metals of choice.
• Later changed to make even easier to use in a
variation called the “crowfoot” or “gravity”
cell.
• Used in telegraph operations to generate
electrical current until 1950’s.

7. Gravity/Crowfoot cell
As Zinc metal changes into zinc ions they
dissolve in the solution, this electrode
disappears. When gone = battery dead!
Cu+2 ions come out of solution, making Cu
electrode larger!

8. Gravity/Crowfoot cell
At a glance, telegraph operators could
look and see how much “battery life”
was left, just like you looking at your %
on your cell phone. Zn crowfoot getting
smaller?? Better get another one ready
to put in!!

9. Gravity/Crowfoot cell
Why called a GRAVITY CELL?
Copper sulfate solution is more dense
and gravity keeps it at the bottom of the
beaker.

10. Gravity/Crowfoot cell
AT night you “recharge” your cell phone.
Basically you’re making the reaction run
IN REVERSE!!

11. Gravity/Crowfoot cell
Calculate the voltage of the Daniel Cell
using Zn/Cu+2
GET OUT AP PACKET!!