### Zinc and The Simpsons

February 17, 2012

This Sunday, February 19, 2012, marks the 500th episode of the popular animated television series, The Simpsons.[1] This irreverent show has always been popular with scientists, engineers, technologists and mathematicians, and for good reason.

My Simpsons avatar.

Many of the writers for the show have
science and math credentials, and jokes concerning science and math make frequent appearances.[2] There is nowhere else on television that you will find Fermat's Last Theorem cast as a joke.[3]

Not that you need to know advanced
number theory to enjoy math humor. Math jokes directed to a public with an elementary mathematics education appeared in movies, as can be seen in this video clip from a 1951 Ma and Pa Kettle film.[4] In this case, an audience with a rudimentary knowledge of arithmetic was expected to find the scene to be funny.

Most of my readers will remember a link between the word, "Simpson," and mathematics from an
undergraduate calculus or analytical geometry course. Simpson's rule, as published by Thomas Simpson, an eighteenth century inventor and mathematician, approximates the area under a curve by calculating the midpoint value between a starting and ending point and applying a trapezoidal area calculation of areas; viz.,

One recurrent theme in The Simpsons is the presentation of boring tutorial films to elementary school children. For those of you who think that advertising targeted to schoolchildren is a recent phenomenon, students of my generation sat through many sports tutorials containing an embedded ad for Wheaties cereal. One film presented to Bart Simpson's class was "A World Without Zinc," that depicted what life would be like without the metal, zinc.

The film's teen protagonist cries, "Come back, zinc, come back!" when he realizes how much of modern life depends on this metal. Actually, biological life as we know it would be impossible without zinc, as stated on The Periodic Table of Videos.[5] A cellphone camera capture of "A World Without Zinc" is available via YouTube, here.

Zinc was an important metal of my own childhood. I enjoyed the Metal Men comic books, the characters of which were robots with qualities that matched their element; e.g., iron was a strongman, and platinum was a platinum blond woman. Zinc appeared in Metal Men, vol. 31, May, 1968, pp. 2,6. Perhaps these comics were my inspiration to pursue metallurgy/materials science.

Also a part of my childhood, in the days before ubiquitous injection-molded plastic toys, were toys made from die cast zinc. Zinc is an excellent material for die casting. It's a relatively benign metal with a low melting point (419.5 °C). Not-so-benign mercury, gallium, lead, bismuth and cadmium, among others, have lower melting points. Zinc is used less frequently than only three other metals, iron, aluminum and copper. It's also inexpensive, being currently about one US dollar per pound.[6]

Hubley Realtoys 1958 Ford police vehicle, made from painted, die-cast zinc.

(Photo by C. Steven Campbell, via Wikimedia Commons))

One of the most important uses of zinc is for galvanization, a method to forestall the corrosion of steel. A zinc coating, applied by electroplating, but more usually by dipping the article into molten zinc, is used as a sacrificial anode in corrosion reactions. The presence of the sacrificial anode disrupts one of the two half-reactions responsible for the formation of iron rust; i.e.,
Fe -> Fe2+ + 2e-
The downside is that the sacrificial anode is corroded, instead, but there's a net advantage to the lifetime of the steel structure.

Many years ago, my family discovered zinc throat lozenges as a common cold remedy. This patented [7] delivery mechanism for the active ingredient, zinc gluconate, has been shown in one clinical study to markedly reduce cold symptoms. Coughing and cold duration were essentially cut in half.[8] One tip, as advised by the manufacturer, is not to use these on an empty stomach, or you might be moaning, "Why, zinc, why!"

EX ZINCO, MULTO

US Lincoln pennies dated 1983 or later are copper-plated zinc (97.5% Zn, 2.5% Cu).

Earlier coins, except 1943, which were zinc-plated steel, are 95% copper.

(Via Wikimedia Commons)

### References:

1. The Simpsons on the Internet Movie Database.
2. Sarah J. Greenwald and Andrew Nestler, SimpsonsMath.com Web Site.
3. Fermat's Last Theorem in Fiction on Wikipedia. The Simpsons episode, "Treehouse of Horror VI," presents the equation 178212 + 184112 = 192212, which is valid to twelve digits, but false by Fermat's Last Theorem (since proven). The Simpsons episode, "The Wizard of Evergreen Terrace," presents the equation, 398712 + 436512 = 447212, valid to ten digits, but also false.
4. Ma and Pa Kettle Back on the Farm (1951), Wikipedia Page; Ma and Pa Kettle Back on the Farm, 1951, Edward Sedgwick, Director, on the Internet Movie Database.
5. Zinc (version 1) - Periodic Table of Videos, via YouTube; Zinc - Periodic Table of Videos, via YouTube.
6. Mineral Commodity Summary - Zinc, US Geological Survey, 2012.
7. John C. Godfrey, "Flavor of zinc supplements for oral use," US Patent No. 4,684,528, August 4, 1987.
8. Jonathan Chait, "Come Back, Zinc! Come Back!" The New Republic, February 16, 2011 .

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