Chemistry and Physics

We perpetuate some stereotypes about scientists.

We mentioned a few weeks ago that one of our consultants had repaired and re-seasoned a cast-iron pot.  The main problem was not the re-seasoning, which was described in that post; it was the fact that the pot was heavily rusted to begin with.  It did not respond to normal cleaning, even with steel wool.  Attacking it with firm resolve, industrial-grade steel wool and heavy work gloves resulted only in highly-polished rust.  Suggestions from some quarters ran to sandblasting; unfortunately, we have no such equipment here at Five Colors and there are none in the vicinity.  Cooking in a rusty pot is probably not poisonous, but is certainly unappetizing.

A chemist friend suggested something, which chimed with remarks made by our Navigator from his Navy time: soft drinks contain some chemicals that are remarkably useful, if you don’t drink them.  An application of Coca-Cola® ate the rust.  Two applications, just to be sure, and the pot was ready for seasoning.  (Important: we are not recommending this for everyone, another brand might work as well, Coke® might not work at all in your case; we’re reporting our experience, not giving advice.)

Our chemist, of course, set out to figure out what was happening.  The drink contains mostly water, sugar and caffeine, none of which would have any effect on ferric oxide.  The active ingredient seems to be phosphoric acid.  It’s there to lend some tartness to the taste; just by chance it reacts with rust.  There’s no need to worry about its effects on your stomach (unless you take the Iron Man competition much too literally); the sugar and caffeine have much stronger influences on your body.

But while our chemist eventually found the reaction involved, he’s still frustrated.  Based on his texts and references, he would never have predicted it.  It doesn’t fit well among the systems he learned and which our tutor helps students to learn.  Chemistry is complicated.  Especially in real life.

Consider one aspect that students are expected to learn: what substances are soluble in water?  All the chlorides, except silver chloride and lead chloride and maybe some others; phosphoric acid but not ferric phosphate; a whole table of rules and exceptions.  Students regularly complain about the sheer mass of what they’re expected to learn, and are often confused about whether they’re supposed to be able to predict things or just memorize them.

Compare Physics (at the High-School level).  There are Newton’s Three Laws, supplemented by some rules for friction and gravity.  Most of the time is spent on working out how to use them, how to apply them to new situations.  The sheet of formulas students are allowed to take into tests is the size of a postcard, even if the writing is not particularly small.

We think this is because chemistry, as a subject, has its roots in practical problems.  It grew out of the demands of industrial life and has always been a bit disordered.  Physics, as we know it today, came from the motions of the planets and the swings of a pendulum, idealized experiments (whose descendents live on in introductory Physics labs).

Hence our characterization of the respective students.  Physics majors drink wine, work crossword puzzles and are certain that, if they don’t know everything yet, they will after next semester.  Chemistry majors drink beer, are fond of bad puns and know that when the chemicals are put in the test tube, they’ll do whatever they damn well please.