Chemistry | Balancing Redox Reactions

I was catching up with my friend Scott on the phone the other day... to be honest, friend is a huge understatement. Scott was my college advisor, developmental biology professor, summer employer, mentor, helped me get my first job out of college, and helped me get my first Softimage license so many years ago. My son's middle name is Scott because the real Scott is such a mensch, so let's call him my mentor because no friend ever did so much while asking for so little. Scott knew my mind when I was a student, and he knows me now, so I have been asking his advice about returning to school after all these years.

Scott brought up an old routine by Father Guido Sarducci called the Five Minute University, the gist of which is in five minutes you can learn everything you would remember from school five years after graduation. For example, if you took two years of Spanish, five years later you'd most likely have forgotten all the vocabulary and conjugation rules, so for Sarducci's FMU, all you need to learn is "Como esta usted" and "Muy Bien." Want to take the FMU economics class? Supply and Demand. Buy Low, Sell High. The cost of tuition at FMU is $20.00 per student, which might seem like a lot, but also includes snacks, photo of cap and gown, and diploma.



While the FMU approach might be acceptible for most job applications, it's not going to suffice for my personal ambitions. So in the spirit of the contrarian that I am, I decided to go back and review General Chemistry, and more specifically to see if I could rekindle the process of balancing Redox reactions, something I remembered from AP chemistry in high school. Coincidentally, in my experience AP chemistry was a class where students frequently asked the question, "Do we have to know that for the test?" The teacher was fond of replying "Some people drink from the fountain of knowledge, others just gargle." Most of us could tell that the meaning of that quip went over the heads of the intended targets. It was only years later I noticed that same line in Bartlett's Familiar Quotations which was attributed to Robert Anthony Newton, a famous accounting professor at the Harvard Business School, and not my high school chemistry teacher. Bummer.

The art of balancing chemical equations in general is called "stoichiometry", and for real basic equations you only have to make sure the number of atoms on the left side equal the number of atoms on the right side. That's easy enough to qualify for FMU status. I remembered Redox reactions being much more difficult, because they have hidden attributes dealing with electron transfer and balancing charges and water molecules with acids and bases.

Talking about oxidizing and reduction agents, double displacement reactions, titrations, molarity, and molality, that may sound obscure to 98% of the laypopulation, but those words can strike terror into the minds of anyone taking general chemistry, and they are definitely out of the scope of the FMU curriculum. I've spent many hours of the past few weeks practicing stoichiometry and balancing Redox reactions (sorry Father Sarducci) and here's my recipe:

1) Break the reaction into two half-reactions.
2) If the oxidation states of the non Oxygen, Hydrogen atoms are obvious to calculate, figure out which species is being oxidized, which one is being reduced, then add free electrons to that half-reaction.
3) If the oxidation states are not obvious, balance the charge with H+ for acidic reactions, or OH- for basic reactions, then balance the Oxygen and Hydrogen in the half-reactions with H2O. Balance resulting charges with free electrons.
4) Using multiplication of all half-reaction species, equilize the number of electrons in each half -reaction so they can cancel out when the two half reactions are added together.
5) Add the two half reactions, canceling out the extra H2O's, H+'s or OH-'s

Coming up next? The chemistry of gases. The FMU part of my brain only remembers the words "Boyle's Law", the phrase "Standard Temperature and Pressure" and the formula PV=nRT.