Thursday, August 19, 2010
Chromatography: The Basics
The water will travel up the filter paper. As it travels, it will carry some of the ink with it. The ink that is made of larger molecules will not travel very far. The smaller molecules will travel farther up the paper, resulting in separation.
Now, here's how I use it in my classroom...
I usually make a sign with a silly threat on it. Something along the lines of, "8th graders small funny." Mature, right? It's enough to get the students attention and I tell them that we're going to figure out who wrote it.
I then go through a story. Something like... "Mr. Krup always has a black Sharpie. And I saw Dr. Smith with a black Crayola marker yesterday. Etc." I use names of teachers in the school - people who are my friends and are good sports.
The students each get a piece of the threat that contains some ink, so they can use it for chromatography.
Then, they take a wider strip of filter paper and make a mark with each of the 'suspect' markers.