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Clear Or Colorless Conundrum

June 8, 2009 | A version of this story appeared in Volume 87, Issue 23

I am always delighted to open my issue of C&EN and find a new "What's That Stuff?" item. I post each new article outside my office so students can read about the chemistry behind the materials they use and consume.

I was especially interested to read about "self-darkening eyeglasses"(C&EN, April 13, page 54). Thus, I was a bit dismayed that the author chose to describe these glasses as "dark or clear." If I didn't know better, I might interpret this to mean that, when darkened, the eyeglasses were not clear—and that would seem a dramatic drawback to wearing sight-correcting glasses.

My students struggle with the concept of "clear and colorless," too, and most will initially describe the color of a sodium hydroxide solution as "clear," which, they are reminded, is not a color. After a bit of head-scratching and some prompting, they eventually realize that "colorless" more accurately describes the color (or lack thereof) for this particular solution. This exercise might seem picky, which I don't deny; after all, I know what they mean. But one of my objectives as a teacher is to demand that students be accurate in their descriptions—something that pays benefits to everyone when reading and writing the scientific literature.

Christopher M. Bender
Spartanburg, S.C.


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