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We're going to show you how you can actually measure the thickness, or diameter, of a single molecule. To do this experiment, you'll need a large flat-sided shallow pan of some sort, a straight wire or thin rod at least as wide as the pan, and a small amount of oil of any kind. You will see the oil spread out across the surface of the water on that end of the pan, right up to the wire. Wait until that end of the pan is completely covered by the oil before proceeding. You now have a layer of oil that is one molecule thick! (If the oil layer doesn't seem to break up at all, then either start over with an even tinier drop of oil, or find a larger pan. The pan from the bottom of a travel kennel for a large dog might work.) If the length and width of the oil blanket (the pan) turn are, for example, 400mm and 300mm, the following calculation shows how to solve for H:
This makes the height of the oil blanket, or the diameter of one molecule, equal to 0.00000833 mm, or 0.00000000833 metres. Given the inaccuracy of our measurement, it's probably safe to round this number to 0.00000001 metres, which is one ten-millionth of a metre, or 10-7 m. Since an oil molecule has many atoms in it, this isn't the size of an atom, but the thickness of the entire molecule. With this simple calculation, we've measured the thickness of one molecule of oil, an object which is too tiny to see in an ordinary microscope! |