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Water Posted March 18, 2001 It looks like we made it through the winter, and things are starting to look a lot like springtime. And that can only mean one thing: lots and lots of water. You might be thinking about how you're going to get all that water to come down the mountain, without getting into your house. Or you might be sadly watching the snow melt, thinking about all those months that you're going to have to live through without snowboarding. Not me. I'm thinking about all the special chemical properties of water, and the funny things water does for us, like heat our houses, cool our car engines, and freeze, so we can skate. I'll mention a few of the unusual things about water, like the fact that a lot of people know it's H2O, but first you should listen to this arrangement for two pianos, of the overture to the Magic Flute. And immediately after that, the same pianists will play you the overture to the Marriage of Figaro. And if I have enough time, I'll go even further, and also let them play the overture to The Barber of Seville. That's not a Mozart opera, but the overture was definitely influenced by the Magic Flute. While you're listening, if you have any science questions you'd like me to answer, you can give me a call in the studio at 352-3706. And if you can't remember what your question was until after the show, you can leave a message for me at the KCR office number, 352-9600. --- Zauberflote d2 t17 You're listening to Mostly Mozart on Kootenay Co-op Radio. Comfort and Joy is happy to sponsor Mostly Mozart. My name is Tom Clegg, and today's show is all about water. Spring run-off, and all that. The first thing I'd like to say about water is that when I came to Nelson, one of the first strange things I noticed about this place was that there's a huge mall parking lot right on the lakeshore. Not even a mall - a mall parking lot. What a weird way to use lakeshore property, I thought. Last week I went to that meeting in the Hume Room, and I found out that I wasn't the only one. Apparently Nelson made the funny papers all across Canada, for being the first city with a lakeside mall parking lot. I would have found this funny myself, except that the only reason I went to the Hume Room in the first place was the possibility that Nelson is also going to be the second city in Canada with a lakeside parking lot, as well as the first. Strange times we live in. But I digress. Water is H2O, as you know. When it's frozen, it's ice; when it's vapourized, it's steam. Unless it's not hot enough to be steam, in which case it's just humidity. When it's got lots of positive ions, it's acid; when it's got lots of negative ions, it's basic, or alkaline. Water has some rather extreme properties. One thing you've probably noticed is that it's very heavy. Also, when it's hot, it's very hot, and when it's cold, it's very cold. Although, ironically enough, if you make an igloo out of frozen water, it can be reasonably warm inside. Try leaving a bucket of water and a block of dry wood outside overnight. Pick up the block of wood in the morning. It will feel a bit cold. Stick your hand in the bucket of water. It will feel a lot colder. They're at the same temperature, but water feels colder because it has a high specific heat capacity. Heat capacity, which you could just as well think of as energy capacity, is a measure of how much energy it takes to raise the temperature of a given substance. Water absorbs lots of energy as it heats up, and when you stick your hand in a bucket of cold water, that's what happens. The water absorbs heat energy from your hand, and your hand gets very cold, while the water gets very slightly warmer. You can try the opposite effect as well. Or more likely, you've already had the opposite experience and you hope you never do it again, but you know you will. If you haven't done this yet, don't try it now, just feel lucky. If you put your hand over a boiling kettle, you get something called a steam burn. It happens a lot quicker than you think, so by the time you notice your hand getting hot, it's too late, you've got a big red mark on your skin, and it really hurts. Even though steam takes up a lot more space than the same mass of water, it still has that high specific heat capacity. When those steam molecules touch your skin, they release a huge amount of energy, as they try to achieve thermal equilibrium with your hand. When your skin absorbs enough energy from the steam, it the steam condenses and becomes very hot water. That's right, boiling water on your skin. The heat transfer continues, but now with more molecules in a smaller space. And if that weren't bad enough, you've probably still got new steam coming from the kettle, to ensure that the water never cools down enough to become comfortable. Until you move your hand and stick it in cold water or something like that. I can't give you medical advice on this show, but personally, when I find myself getting a steam burn, I take my hand out of the steam. So that's just one way to hurt yourself with water. Here's another one you can save up for the next time someone says something silly like, "a little water never hurt anyone." Like many of you, I used to live in Ottawa. One of the cool things about Ottawa is the copper roofs on the parliament buildings. But they don't have anything to do with water, do they. Well, yes, they do. Last time I saw those copper roofs, they were, well, copper coloured. But traditionally they are an unusual shade of green. And if you've seen pictures of the parliament buildings when the roofs are green, and you think they look funny, you should see them with copper coloured roofs. It's even funnier. In any event, copper turns green when it rusts. And as I've mentioned before, rusting is oxidization. And guess where the oxygen comes from? H2O, in the form of rain and humidity. But I wanted to talk about how to hurt yourself with water, and I wasn't thinking about jumping off the roof of the library of parliament. I was thinking about another of the cool things about Ottawa, and that's the Rideau Canal. One of Canada's favourite pieces of propaganda, which may even be true, is that the Rideau Canal is the world's longest skating rink. Usually they say this in the same paragraph where they mention that the Rideau Canal connects Kingston and Ottawa, or something like that, so you think the skating rink is 100 km long. It's not really; the skating part is just between Dow's lake and the locks at the Ottawa River. But even at 5 km, it's long enough. If you've ever been skating on the Rideau Canal, you probably know exactly how to hurt yourself with water. You just have to build up your confidence over the first few days, then skate really really fast, building up momentum over 50 metres or so, and then for no good reason, you turn one way with your feet while turning the other way with your shoulders. You spin around a few times, and eventually land on your hip bone or something. Fortunately you don't scrape yourself or tear your clothes, because the ice is pretty smooth, but it hurts anyway because the ice is so damn hard. Which is good when you're driving a snow plow on the canal, but very unforgiving when you're falling on your hip. But wait a second. Why is there ice on top of the water? If the coldest water is at the bottom, which you know if you've ever been diving, why isn't the ice also at the bottom? One of the unusual things about water is that it expands just before it freezes. When it expands, it becomes lighter, so it floats to the top. This makes skating a much less soggy experience. It also allows fish to survive the winter by living under the ice. Although in case you're wondering, no, there aren't a whole lot of fish living in the Rideau Canal. At the same time, water is plentiful and scarce. We've got oceans, five miles deep, full of water. But there's salt dissolved in it, and that makes it useless for drinking purposes. There's also a lot of oil floating around on it, and a few hundred years of miscellaneous industrial waste. We've also got huge natural drainage systems all over the earth, and they provide a convenient source of naturally filtered water... until we start dumping our sewage and garbage into them, and cutting down all the trees whose roots and friends are supposed to be doing the filtering. But I think I already complained about that a couple of weeks ago, so I'll leave off there. Mostly Mozart is sponsored by Comfort and Joy, a unique children's store. My name is Tom Clegg, and I'll be back next week at this time with more Mozart and more science. If there's something in particular you'd like to know, I'd love to hear from you. Call me in the studio at 352-3706, or leave a message at the KCR office, at 352-9600. The rest of today's show is Mozart's piano concerto number 9, "Jeunehomme". That's right "Young Man". But it is Mozart, not the Village People. It's performed by our friend Angela Cheng, with some help from the CBC Vancouver Orchestra. Thanks for listening. See you next week. |