Perchlorate-ClO4
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Post: 56007479_1 created on Sat Nov 07, 2009 2:47 amPosted: Sat Nov 07, 2009 2:47 am
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So I had a huge throw down with my chemistry teacher in the middle of class over two issues.
One is significant figures. Significant figures of a number are those digits that carry meaning contributing to its precision. Rules concerning significant figures as I have been taught: * 1. All non-zero digits are significant. * 2. In a number without a decimal point, only zeros BETWEEN non-zero digits are significant (unless a bar indicates the last significant digit--see below). * 3. In a number with a decimal point, all zeros to the right of the left-most non-zero digit are significant. For multiplication and division, the result should have as many significant figures as the measured number with the smallest number of significant figures. For addition and subtraction, the result should have as many decimal places as the measured number with the smallest number of decimal places. Now she gives us the problem, for an example, how many seconds are in 8 hours? The answer is 8 x 60 x 60 = 28,800, but due to the need for significant figures she says we have to round it to 30,000 to match our original number of 8. My problem with this is that: It is inaccurate, just wrong. There is no confusion about our ability to measure this. The increase of significant figures is justified because we have unit measurements for minutes, seconds, and their ratio to hours. After this argument, which I seceded because my teacher wouldn't back down, and I wasn't going to make an a** out of myself any further, I took time to think about this some more. But not about the significant figures, this time it was about measurement as a whole. I remember around last year I rented a book from the library written by Plato. In it he presented an allegory of a cave, in which he describes how our perceptions influence our view of the world, and how we are unable to deal with new perceptions or concepts with out coming off as crazy, or even going crazy. Now perhaps I am too young to have understood it right, and if so please let me know. It is not my intention to mis-comprehend. Now after thinking about this I decided to try a thought experiment. You have a blind man who wants to learn about the world around him. Nobody can help him. There are no poisons or harmful substances in this world. In order to do so he makes tools to measure the objects of his world. He tastes them, smells them, and feels them. After he does this he has the precise measurements and data of all things in his world. Does he have an accurate image of the world? Does he, having done all this, truly know the world around him as it is presented independently of him or others thoughts about it? Now with us, though we are not blind, with all our tools and technology, do we really see the world as it is independently of us? For all the precision our instruments have, how accurate is the data it gives us? |
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