Ideas about Rates

What do students already know about rates of reaction? Clearly, they have seen Alka-Seltzer bubble in a glass of water, or have at least seen a commercial about it. Many students know that iron rusts in the rain. I asked two students in a sophomore level chemistry class about the rates of nails rusting. One of the students told me that chemical changes take a long time, just like a rusting nail. She knew that the rusting of a nail does not happen in a short period of time. This is her basis of knowledge about rates. In her mind, she has already set up a timetable of reactions. If the students come into the lesson already having an idea of about how long it takes to proceed with a reaction, they will be better equipped to tackle some more difficult information.

We see in "The Having of Wonderful Ideas and Other Essays," an article by Duckworth, that there are many instances where the reactions become a bit fuzzy. She cites the steel wool experiment in her article. Duckworth, like many of the students will be after viewing the results, was intrigued by the fact that the water levels were exactly the same in each of the tubes. If you were able to plot the height of the water versus time, you might see that in fact, the rate of water filling into the tube is almost exactly the same. Although she didn't mention it exactly, her idea that water fills to the same level is in fact just saying that the rates of reactions between the tubes are identical.

It is my guess that many students know that rates govern their lives. I have a feeling, however, that students do not realize the importance of enzymes and catalysis to their lives.

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