It is Labor Day, and I am writing this while watching a show on Scandinavian cooking. The meal he is fixing consists of cooked carrots, baked celery root, and grilled pork chops. It was served with a cool glass of beer and looked grand.
Except for Friday, when I apparently made two young ladies cry, last week was a pretty good week. The crying had nothing to do with anything I said; it was, apparently, induced by a particularly difficult homework assignment. The first girl approached me before class to inform me that she could not do several of the problems on the assignment that was due that day. She asked for some help, her eyes swelling up with tears as she spoke. Being a man, I am not very good at dealing with an upset woman. I tried to comfort her by pointing out that the problems in question were worth only a few points in a 50 point assignment. This did not seem to make her feel any better as she said, in a breaking voice, “I never wasn’t able to finish a homework assignment before—not ever.” At the end of class another girl came up to me and said that she needed help; informing me that her homework was a mess and she did not understand anything. She wanted to know if I was going to send her down from honors chemistry to a regular level class. Then she began to cry, saying that she did not want to drop down. I told her that it was too soon to make that decision and that she should wait, at least, until she took the first exam. Both girls did much worse that the average on the assignment.
I am sure that I appeared quite hard and unemotional to both young ladies. What I wanted to say to both was, “Stop! There’s no crying in Chemistry!”, but that would have been insensitive. I am not an insensitive man—even if I don’t know how to handle a crying female. I tried to comfort each; letting them know that it wasn’t as bad as they thought and that many others had trouble with the same problems. Both of these statements were lies. The problems they had trouble with were simple density calculations, and the fact that they were completely stumped by them was a sure sign that neither belongs in Honors Chemistry; as well, most other students did them without turning into jelly. If either of them does poorly on the exam Wednesday, I may have to recommend that the drop down; though, I will not demand that they do.
The main problem each had difficulty with is given below:
Oxygen gas has a density of 1.43 g/L at a given temperature and pressure. What mass of oxygen gas is contained in a spherical balloon with a diameter of 15.0 cm? The formula for the volume of a sphere is 4/3∏r3.
In order to solve this problem you have to recognize that mass can be determined by multiplying density and volume. The density is clearly given in the problem, but the volume has to be calculated by using the formula for a sphere that was given, and knowing that the radius is half the diameter. Since these are all honors students, and all of them have to be in honors math, I would expect that they could make their way through the calculation without help. While this was true for most of the students, it was not for these two girls. We covered standard density problems in class the day before. After the exam on Wednesday I will have to check for other students who might benefit from some extra help, or by dropping down.
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