Wednesday, September 07, 2005

Test Bad! Answers Good?

Well, I got back from my first Chemistry exam just a few hours ago. I think I did okay, but it was a little weird. I know I screwed up on the last answer a bit. We had to circle which elements were metals, non-metals, and metalloids, on the periodic table. I got most of that down pat, but I think I screwed up on some of the metalloids. I remembered they made a diagonal pattern between the metals and non-metals, but it’s not a perfect diagonal. It’s more like a diagonal with exceptions (does that make it an exceptional diagonal?). It’s too bad, too. That question was worth more than any of the others.

There were two questions that threw me, though. Not because they were hard, but because what I think are the correct answers weren’t available. One was determining the specific gravity of a substance. They listed the mass and volume, so I could figure out the density, and then the specific gravity. The problem is that with specific gravity all of the units cancel, and so you’re left with just a number. No units. The mass and gravity were given with three significant figures. The correct number, with three significant figures, had units listed by it (g/ml), and specific gravity doesn’t have units. There was another answer that had no units, but not the correct number of significant figures. So which was right? I called my professor over and asked him about, but all he said was “If you think that’s the right answer, don’t worry about the significant figures.” That’s sort of like saying, “One of us screwed this up, but I’m not going to tell you which one.”

The other question that threw me was when we were asked to show the function of certain trace elements in regards to human health. It was a sort of “mach the element with the function” kind of thing. Trouble is he gave one element that didn’t have a matching correct answer, and one answer that didn’t have a corresponding element. I crossed off all the functions as I matched them up with the elements, and I was left with the element Molybdenum and the function “essential element found in body fluids that supports nerve function.” According to my crib sheet, Molybdenum is useful in enzyme metabolism. Potassium supports nerve function. I made a note of it at the bottom of the sheet, but I’m worried I may just have annoyed my professor. Either that or I got it wrong, and I don’t think I’m wrong.

Maybe I’m just becoming arrogant. I guess I’ll find out tomorrow.

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