Transcript Kinds of Chemistry - Louisiana State University

Announcements
Today’s lecture is brought to you
by the number…
10
Electron Transfer Reactions*
Oxidation & reduction
(revisited)
Geez….almost all reactions are this!
2
Hindenburg: oxidation of hydrogen by
oxygen, reduction of oxygen by hydrogen.
http://www.youtube.com/watch?v=CgWHbpMVQ1U
http://www.youtube.com/watch?v=xiAT9xvTVKI&feature=related
2H2  4H+ + 4e4e- + O2 2O2_____________________
Oxidation Half Rxn
Reduction Half Rxn
2H2 + O2  4H+ + 2O2-  2H2O
RedOx means Reduction and Oxidation;
They go hand-in-hand.
Reduction
Oxidation
Lose oxygen
Gain oxygen
Gain hydrogen
Lose hydrogen
Gain electrons
Lose electrons
This is the “smoke on the water”
reaction we saw on video.
2Na + 2H2O  2Na+ + H2 + 2OH+ e (electron lost)
Na was oxidized: Na 
H was reduced: lost oxygen
O no change: lost H but gained eNa+
Remember…we can actually run this reaction by dumping
some sodium into water.
ReDox in organic systems is tricky.
2 CH3OH  2 CH2O + H2
C:
H:
H:
O:
???
???
???
???
This one is very tricky (and related
to “butter vs. margarine”)
CH3CH2CH2CH=CHCH2CH3 + H2 
CH3CH2CH2CH-CHCH2CH3
H
C ?????
H ?????
H
Not-so-Secret Agents: all part of the
semantics nightmare that is RedOx
Something that promotes reduction: reducing agent
Example: K, Na, H, LiAlH4
Something that promotes oxidation: oxidizing agent
Example, O, F, Br, K2Cr2O7
Main Applications of RedOx
Recovery of metals from ores
Corrosion
Prevention of corrosion
Batteries
Steel!
And the sons of
Pullman porters & the
sons of engineers
Ride their fathers'
magic carpet made of
steel
Mothers with their
babes asleep, rockin' to
the gentle beat
And the rhythm of the
rails is all they feel
City of New Orleans—
Steve Goodman
A country that makes stuff makes steel.
Reducing Iron Ore to Make Steel:
from rust to riches
2 Fe2O3 + 3C  4 Fe + 3CO2
Rust
i.e., ore
From
Coal
How steel is really made: http://www.sidmar.be/CONTENT/2c.htm
RedOx contributes to our geography,
history and economics.
IRON ORE
CARS COAL
Why a steel factory in Louisiana?
Electro-reduction for aluminum
production takes much energy.
2Al2O3  4Al + 3O2
http://www.terragalleria.com/images/us-ca/usca10035.jpeg
http://www.ocrwm.doe.gov/youth/images/powerplant.jpg
Electrons supplied
Electrons returned
Power Plant
http://www.epa.gov/highgwp/aluminum-pfc/images/exhibit3.gif
Aluminum production affects/has affected geography, too.
Hydroelectric
Power
Aircraft Industry
Hydroelectric
Power
Why do we recycle aluminum?
http://www.recycle.novelis.com/Recycle/EN/Kids/Fun+Facts/Many+Lives+of+the+Aluminum+Can/
Corrosion is the auto restorer’s enemy!
2 Fe  2 Fe+2 + 4 eElectrons travel down nail
4e
+ 2H2O + O2  4OH
http://cardesign.homestead.com/BaraMtn72.jpg
Rust on my Barracuda
 Someday, someday…
Batteries! What if we could trap
those electrons, make ‘em do some
work before the reduction step?
ENR vs XOM
Fuel Cells—a quick intro to why we need
chemistry and chemical engineers.
Honda FCX fuel cell concept at
~100 mph on a test track.
It goes 354 miles without
refueling with hydrogen.
How soon? Soon!
http://www.youtube.com/watch?v=y3VtrzcKQk
Hey…where are we gonna get the
hydrogen?
Images from treehugger.com (no kidding, that’s the site!)
We are reliant on foreign oil.
http://www.worldfuturefund.org/wffmaster/Charts-HTML/Energy/us-oil.htm
But
maybe
not
forever,
U.S. oil
imports
thanks (?) to fracking to
as a percentage
of consumption
recover natural gas.
http://www.saudi-us-relations.org/newsletter/saudi-relations-12.html
http://ils.unc.edu/~lanck/images/Roosevelt.jpg
Let’s go to the fabulous HowStuffWorks
site to see how Fuel Cells work.
Clickable: http://auto.howstuffworks.com/fuel-cell3.htm
Pasteable: http://auto.howstuffworks.com/fuel-cell3.htm
So, what are the technical challenges?
The hydrogen has to come from somewhere.
Transport of the protons across the polymer membrane
requires the membrane be hydrated and liquid.
The membrane (think of it as a sulfonated teflon) is
expensive and can be damaged or fouled.
The electrodes can become fouled.
Expensive metals are used to catalyze the reaction.
About one billion dollars has been
spent so far. Is that a lot?
Approx 5% of the budget of
one of America’s poorest states (LA).
Twelve hundred times less than
estimated project costs of a
certain military intervention in
the Mideast.
Ford and Airstream Concept Fuel Cell Minivan
(N.Y. Times estimate $1200 Billion)
Don’t believe everything you see!
http://www.allthingsbeautiful.com/all_things_beautiful/images/churchill_roosevelt_stalin.jpg
I still haven’t said where the H2 comes from. Look
at this Los Angeles Solar Parking lot, though.
At the other end of I-10 is a windfarm.
Hybrid Vehicles: operate on gasoline with a battery storage system.
RedOx Chemistry Galore
“The car Detroit wants you to believe cannot be built.”
But is that fair???
Hybrid Locomotive: GM is great at this stuff.
Chevy Volt is now selling….slowly.
Cool Fuel Cell Links
How Stuff Works Link:
http://science.howstuffworks.com/fuelcell1.htm
http://science.howstuffworks.com/framed.ht
m?parent=fuelcell.htm&url=http://education.lanl.gov/reso
urces/h2/gottesfeld/education.html
“Maybe I should invest in fuel cells.”
P. Russo, 1999