Janet D. Stemwedel (whose nom de blog is Dr. Free-Ride) is an associate professor of philosophy at San Jose State University. Before becoming a philosopher, she earned a Ph.D. in physical chemistry. Email her at dr.freeride@gmail.com.
A bit of follow-up on the two experiments we described last week:
First off, the water cycle model.
It turns out that the elder Free-Ride offspring used a 20 ounce plastic bottle rather than a 2 liter bottle.
And, there was a mixture of seeds (including radish, corn, and bean seeds), rather than just grass seeds. (We have been speculating about what kind of corn you can grow in a bottle. Baby corn?)
And, the bottle is left uncapped (so the plants have better access to oxygen, and so they don't get all moldy).
And, since it's already an open system (what with the bottle being uncapped and all), we water it every few days or so.
Despite these differences from what we originally described, the system still does a good job with the evaporation and condensation.
Now, about those eggs soaking in vinegar.
Within 24 hours, the shells were completely dissolved. That left the hard boiled egg feeling ... well, pretty much like a hard boiled egg, but a little more slippery. The slipperiness is from the membrane, which usually comes off when you peel the shell off a hard boiled egg. Here, though, we used the vinegar to "peel" it, which left the membrane in place.
Then there's the raw egg:
Here too, the vinegar dissolved the shell but left the membrane. Only in this case, the membrane contains a raw egg. So, we have a squishy bag containing the egg white and the yolk floating in the middle.
The sprogs have been gentle enough with it that the membrane still hasn't ruptured. But I'm not sure it will stay intact indefinitely. In fact, I'm certain this bubble is going to end up bursting.
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Comments
I'm sure you already know this one, but... once you've dissolved the shell from the egg, you basically have a huge cell, so you can demonstrate osmosis. Dissolve the shell from two (raw) eggs then put one in water and one in corn syrup.
Posted by: CK Rock | November 9, 2009 11:01 AM