1 00:00:00,520 --> 00:00:03,800 Speaker 1: Welcome to Brainstuff from how Stuff Works dot com where 2 00:00:03,840 --> 00:00:15,200 Speaker 1: smart Happens. Hi Am Marshall Brain with today's question. If 3 00:00:15,320 --> 00:00:18,800 Speaker 1: water is made up of hydrogen and oxygen, then why 4 00:00:18,880 --> 00:00:23,479 Speaker 1: can't we breathe underwater? One thing about chemicals is that 5 00:00:23,640 --> 00:00:27,639 Speaker 1: once they react in certain ways, they form compounds that 6 00:00:27,680 --> 00:00:31,920 Speaker 1: are often nothing like the original elements. For example, if 7 00:00:31,960 --> 00:00:35,479 Speaker 1: you react carbon, hydrogen and oxygen together one way, you 8 00:00:35,520 --> 00:00:38,960 Speaker 1: get glucose. If you react them together another way, you 9 00:00:39,000 --> 00:00:42,320 Speaker 1: get vinegar. If you react them together in another way, 10 00:00:42,400 --> 00:00:45,320 Speaker 1: you get fat. If you react them in another way, 11 00:00:45,360 --> 00:00:50,720 Speaker 1: you get ethanol. Glucose, Fat, ethanol, and vinegar are nothing 12 00:00:50,800 --> 00:00:53,559 Speaker 1: like each other, but they are all made from the 13 00:00:53,680 --> 00:00:57,920 Speaker 1: same elements. In the case of hydrogen and oxygen gas, 14 00:00:58,200 --> 00:01:01,760 Speaker 1: if you react them together one way, you get liquid water. 15 00:01:02,320 --> 00:01:05,560 Speaker 1: The reason we can't breathe liquid water is because the 16 00:01:05,640 --> 00:01:08,880 Speaker 1: oxygen used to make the water is bound to two 17 00:01:09,040 --> 00:01:13,440 Speaker 1: hydrogen atoms, and we cannot breathe the resulting liquid. The 18 00:01:13,520 --> 00:01:17,440 Speaker 1: oxygen is useless to our lungs. In this form, the 19 00:01:17,480 --> 00:01:21,360 Speaker 1: oxygen that fish breathe is not the oxygen in H 20 00:01:21,440 --> 00:01:25,600 Speaker 1: two O. Instead, the fish are breathing O two oxygen 21 00:01:25,680 --> 00:01:30,520 Speaker 1: gas that's dissolved in that water. Many different gases dissolve 22 00:01:30,560 --> 00:01:33,240 Speaker 1: in liquids, and we can see an example all the 23 00:01:33,360 --> 00:01:38,000 Speaker 1: time in carbonated beverages. In these beverages, there's so much 24 00:01:38,040 --> 00:01:41,800 Speaker 1: carbon dioxide gas dissolved in the water that it rushes 25 00:01:41,920 --> 00:01:46,320 Speaker 1: out in the form of bubbles. Fish breathe that dissolved 26 00:01:46,360 --> 00:01:49,880 Speaker 1: oxygen out of the water using their gills. It turns 27 00:01:49,880 --> 00:01:54,040 Speaker 1: out that extracting the oxygen is not that easy. Air 28 00:01:54,160 --> 00:01:57,680 Speaker 1: has something like twenty times more oxygen in it than 29 00:01:57,720 --> 00:02:01,360 Speaker 1: the same volume of water, plus water is a lot 30 00:02:01,480 --> 00:02:03,840 Speaker 1: heavier and thicker than air, so it takes a lot 31 00:02:03,880 --> 00:02:06,920 Speaker 1: more work to move it around. The main reason why 32 00:02:07,040 --> 00:02:10,120 Speaker 1: gills work for fish is the fact that fish are 33 00:02:10,160 --> 00:02:15,600 Speaker 1: cold blooded, which reduces their oxygen demands tremendously. Warm blooded 34 00:02:15,639 --> 00:02:19,120 Speaker 1: animals like whales breathe air like people do because it 35 00:02:19,160 --> 00:02:23,720 Speaker 1: would be hard to extract enough oxygen using gills. Humans 36 00:02:23,800 --> 00:02:27,639 Speaker 1: can't breathe underwater because our lungs don't have enough surface 37 00:02:27,680 --> 00:02:31,600 Speaker 1: area to absorb enough oxygen from water, and the lining 38 00:02:31,600 --> 00:02:35,600 Speaker 1: of our lungs is adapted to handle air rather than water. However, 39 00:02:35,720 --> 00:02:39,560 Speaker 1: there have been experiments with humans breathing other liquids like 40 00:02:39,639 --> 00:02:43,960 Speaker 1: flora carbons. Flora carbons can dissolve enough oxygen, and our 41 00:02:44,040 --> 00:02:47,480 Speaker 1: lungs can draw that oxygen out. It's just that that 42 00:02:47,680 --> 00:02:50,640 Speaker 1: first breath where you suck in the flora carbons to 43 00:02:50,680 --> 00:02:54,560 Speaker 1: your lungs is not very pleasant. Do you have any 44 00:02:54,639 --> 00:02:58,280 Speaker 1: ideas or suggestions for this podcast? If so, please send 45 00:02:58,280 --> 00:03:01,680 Speaker 1: me an email at podcast at how stuff works dot com. 46 00:03:01,680 --> 00:03:04,000 Speaker 1: For more on this and thousands of other topics, go 47 00:03:04,080 --> 00:03:06,880 Speaker 1: to how stuff works dot com and be sure to 48 00:03:06,960 --> 00:03:09,200 Speaker 1: check out the brain stuff blog on the how stuff 49 00:03:09,200 --> 00:03:10,480 Speaker 1: works dot com homepage