Transcript History of electrochem

Shockingly Brief yet Rich
History of electrochemistry
•Galvani – frog legs~1780
• Volta – battery~1800
•Davy- electrolysis~1820
Chemistry born from dead frogs
Luigi Galvani nasce a Bologna nel 1737.
Physiologist noticed legs of dead frogs
twitched when his steel scalpel touched
brass staples used pin down frog legs
Galvani thought he discovered animal electricity,
but he just found a delectable appetizer!
Allessandro Volta (volt)
• Didn’t buy Galvani’s
explanation
• Enjoying sticking 2
metals on his tongue,
and got same
twitching as frog legs
• Invented the “pile”,
a.k.a battery:
More layers could be
“piled” on to get
higher voltages &
currents
Volta’s pile ~ same 200 yrs later!
Zn anode oxidation (-)
Cu cathode reduction (+)
Electrochemistry under the hood
Making a battery work:
Pick 2 different metals
Standard Reduction Potential (Eo):
- The metal that will act as the cathode, be
reduced, gain electrons has the most
positive potential (electrons flow to +)
Ag+
Cu++
Zn++
Al+++
Eo= +.80
Eo= +.34
Eo= -.76
Eo= -1.7
Example: Cu|Zn has Eo = 1.1V
(zinc is oxidized so it’s Eo sign is reversed)
Electrons flow from negative Cu anode to positive Zn cathode
Davy- cocky inventor of electrolysis
Sir Humphry Davy
Detested Gravy
He lived in the odium
there he discovered sodium
Only scientist besides Newton to be knighted
Contemporary of Volta, Ampere, Gay-Lusaac, assistant was Faraday
Discovered many elements(Na,Ca,Mg,K,Ba,Sr) arc lamps, laughing
gas (N2O), water electrolysis, showed oxidation need not oxygen,CO2
Electrolysis- Davy’s Domain
Volta – 2 different metals produces current
Davy - chemical reactions produce current
Electrolysis- use a battery to drive & even
reverse reactions!
* almost any compound can be oxidized or
reduced using the right voltage!
Electrolytic cell
• non-spontaneous
reactions (negative
total potential) are
possible using a
battery
• Negative end of
battery provides
electrons so reduction
can occur at the
cathode (-)