Announcements

10Electron Transfer

Reactions*Oxidation & reduction

(revisited)

Today’s lecture is brought to you by the number…

2

Geez….almost all reactions are this!

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+ + 4e- Oxidation Half Rxn 4e- + O2 2O2- Reduction Half Rxn_____________________

2H2 + O2 4H+ + 2O2- 2H2O

RedOx means Reduction and Oxidation; They go hand-in-hand. RedOx means Reduction and Oxidation; They go hand-in-hand.

Reduction OxidationLose 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-

Na was oxidized: Na Na+ + e- (electron lost) H was reduced: lost oxygen O no change: lost H but gained e-

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 H

C ?????H ?????

Not-so-Secret Agents: all part of the semantics nightmare that is

RedOxSomething that promotes reduction: reducing agent

Example: K, Na, H, LiAlH4

Something that promotes oxidation: oxidizing agent

Example, O, F, Br, K2Cr2O7

Main Applications of RedOxRecovery of metals from ores

Corrosion

Prevention of corrosion

Batteries

                                                                                            

And the sons of Pullman porters & the sons of engineersRide their fathers' magic carpet made of steel

Mothers with their babes asleep, rockin' to the gentle beatAnd the rhythm of the rails is all they feel

City of New Orleans—Steve Goodman

Steel!

A country that makes stuff makes steel.

Reducing Iron Ore to Make Steel:

from rust to riches2 Fe2O3 + 3C 4 Fe + 3CO2

Rusti.e., ore

FromCoal

How steel is really made: http://www.sidmar.be/CONTENT/2c.htm

RedOx contributes to our geography, history and

economics.

COAL

IRON ORE

CARS

Why a steel factory in Louisiana?

Electro-reduction for aluminum production takes much energy.

2Al2O3 4Al + 3O2

Electrons returned

Electrons supplied

Power Plant

http://www.ocrwm.doe.gov/youth/images/powerplant.jpg

http://www.epa.gov/highgwp/aluminum-pfc/images/exhibit3.gif

http://www.terragalleria.com/images/us-ca/usca10035.jpeg

Hydroelectric Power

Hydroelectric Power

Aircraft Industry

Aluminum production affects/has affected geography, too.

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 e-

4e- + 2H2O + O2 4OH-Electrons travel down nail

Someday, someday…

Rust on my Barracuda

http://cardesign.homestead.com/BaraMtn72.jpg

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.

Images from treehugger.com (no kidding, that’s the site!)

How soon? Soon!http://www.youtube.com/watch?v=y3VtrzcKQk Hey…where are we gonna get the hydrogen?

We are reliant on foreign oil. http://www.worldfuturefund.org/wffmaster/Charts-HTML/Energy/u

s-oil.htm

U.S. oilimports as a percentageof consumption

But maybe not forever, thanks (?) to fracking to 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 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.

(N.Y. Times estimate $1200 Billion)Ford and Airstream Concept Fuel Cell Minivan

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/

fuel-cell1.htm http://science.howstuffworks.com/

framed.htm?parent=fuel-cell.htm&url=http://education.lanl.gov/resources/h2/gottesfeld/education.html

“Maybe I should invest in fuel cells.”

P. Russo, 1999