h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hiya Hell,

Just browsed around this article to see if you said anything about finding the size of the oleic acid molecule, en route to determining Avogadro's Constant. Have you ebver done this? I recently tried it with my students but it was a dismal failure. I discussed it with one of the physics teachers who said he demonstrates it and explains the principle to his students, but they don't actually attempt it as a class practical. I think I'll adopt this approach in future.

It is just incredible what you can do with the method I show in this Entry But no, I never felt particularly interested in devising Loschmidt's number this way... Maybe because I am not a teacher

But I have calculated the molecular size of many compounds just in this way. I even had them on posters and suggested putting them on a publication. My boss thought this was a bit too 'yopsil-mopsil'... err... dodgy...y'know... Well. In the end we had a theoretician do the calculation for us. Two months later and according to him I was 4% off. When the x-ray structure became available it turned out I was right, and the computer calculations were off by 4%. (Now imagine my triumphant ego at that time)

In the meantime I have been practicing this with every formula I find intersting. It usually works to some 10%; which I think is fair enough if you consider that the bigger molecules are gooey anyways.

HELL

PS: Actually I am very glad *someone* read this Entry. H.

You'd be urprised at some of the stuff I end up reading. As I say on my PS, "I've got a very eclectic range of interests". To be honest, I think this is why I am a teacher; I enjoy learning new things about various areas of my interest and "the best way to learn is to teach".

Same here, BigAL... But I am a very lousy teacher (according to some of *my* students -- I am not a teacher at school, but I have to give lectures and do exercise classes in university). This is why I think writing stuff for h2g2 helps me so much in articulating ideas. Everytime a student comes with a 'primitive' question I end up thinking this would be a great topic for an Entry. Next time I'll just give him the link and tell him to shut up. (... well...nah... I don't think I'd *say* that... but I think you get the picture.)



HELL

"What I hear I forget,
what I see I remember,
what I do I understand."
CONFUCIUS ~AD500

......But it is only when I teach I truly learn!
J D Gilbert 1992