truthlover responds to me:
quote:
Why are they saying "virtually all."
Because no chemical reaction is perfect. Remember the postulate: "Strongly associated." We realize that just because we have a test, that doesn't mean it's going to catch every single case.
You know those pregnancy tests? Just because the little line/dot doesn't appear/disappear doesn't mean you're not pregnant. There are women who have given birth who never tested positive for pregnancy through the chemical tests.
I'm famous for my chemical experiments not going right. Scared the hell out of a chemistry prof of mine. It was the first lab and it was the typical one of establishing procedure: You're given five chemical solutions and you mix each one with the others in order to determine what sort of reaction takes place (precipitate, change of color, sulfurous odor, etc.) Then, you're given the same five solutions but this time unlabeled and, using the information you acquired from the first part, you need to identify which is which.
Well, none of my chemicals would react. The professor came by, looked at my notebook, and asked me why I wasn't doing the experiment since I didn't have anything written down. I told him that I was doing the experiment and it wasn't very nice of him to give us stuff that was so weak it wouldn't react. He harumphed, took a test tube of mine, added some solution from two of the bottles, shake-shake-shake, and all sorts of precipitate starts falling out. Oh yeah, I reply? Watch. I take the same test tube, clean it out, take the same two solutions, shake-shake-shake, and see? Nothing!
His eyes nearly popped out of his head.
But I wasn't done. Next experiment was to create alum from a soda can. You take a piece of aluminum, run it through a chemical bath to create a salt, and then dry the crystals. The idea is to measure yield rates.
Well, the chemical solution part of the reaction was only supposed to take about 20 minutes. But with me, it was taking more than two hours. The reaction took place over a hot plate in order to make it run faster and I was in danger of boiling off all of my liquid leaving nothing to react with the aluminum square that was simply refusing to dissolve. This time, he had to go get the head of the chemistry department to help figure out what the hell was going on and how to save the experiment...especially with not enough time to complete it.
Rrhain
WWJD? JWRTFM!