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10 Electron 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 H 2  4H + + 4e - Oxidation Half Rxn 4e- + O 2  2O 2- Reduction Half Rxn _____________________ 2H 2 + O 2  4H + + 2O 2-  2H 2 O

RedOx means Reduction and Oxidation; They go hand-in-hand. ReductionOxidation Lose oxygenGain oxygen Gain hydrogenLose hydrogen Gain electronsLose electrons

This is the “smoke on the water” reaction we saw on video. 2Na + 2H 2 O  2Na + + H 2 + 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 CH 3 OH  2 CH 2 O + H 2 C: ??? H: ??? O: ???

This one is very tricky (and related to “butter vs. margarine”) CH 3 CH 2 CH 2 CH=CHCH 2 CH 3 + H 2  CH 3 CH 2 CH 2 CH-CHCH 2 CH 3 HH C ????? H ?????

Not-so-Secret Agents: all part of the semantics nightmare that is RedOx Something that promotes reduction: reducing agent Example: K, Na, H, LiAlH 4 Something that promotes oxidation: oxidizing agent Example, O, F, Br, K 2 Cr 2 O 7

Main Applications of RedOx Recovery of metals from ores Corrosion Prevention of corrosion Batteries

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 Steel!

A country that makes stuff makes steel.

Reducing Iron Ore to Make Steel: from rust to riches 2 Fe 2 O 3 + 3C  4 Fe + 3CO 2 Rust i.e., ore From Coal How steel is really made:

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. 2Al 2 O 3  4Al + 3O 2 Electrons returned Electrons supplied Power Plant

Hydroelectric Power Hydroelectric Power Aircraft Industry Aluminum production affects/has affected geography, too.

Why do we recycle aluminum?

Corrosion is the auto restorer’s enemy! 2 Fe  2 Fe e - 4e - + 2H 2 O + O 2  4OH - Electrons travel down nail  Someday, someday… Rust on my Barracuda 

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! Hey…where are we gonna get the hydrogen?

We are reliant on foreign oil. U.S. oil imports as a percentage of consumption But maybe not forever, thanks (?) to fracking to recover natural gas.

Let’s go to the fabulous HowStuffWorks site to see how Fuel Cells work. Clickable: Pasteable: 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!

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: cell1.htm m?parent=fuel- cell.htm&url= urces/h2/gottesfeld/education.html

“Maybe I should invest in fuel cells.” P. Russo, 1999