WEBVTT 00:00:00.000 --> 00:00:01.976 [SQUEAKING] 00:00:01.976 --> 00:00:04.446 [RUSTLING] 00:00:04.446 --> 00:00:05.434 [CLICKING] 00:00:14.820 --> 00:00:16.320 JOHN DOLHUN: Good morning, everyone. 00:00:16.320 --> 00:00:19.840 And welcome, or good afternoon. 00:00:19.840 --> 00:00:23.130 Welcome to The Ellen Swallow Richards Lecture Series. 00:00:29.350 --> 00:00:32.320 This is our beloved Charles River. 00:00:32.320 --> 00:00:35.530 This is the river you're going to be testing. 00:00:35.530 --> 00:00:38.770 Once you've tested this river, you 00:00:38.770 --> 00:00:42.550 can actually take this testing and apply it 00:00:42.550 --> 00:00:45.500 to any body of water. 00:00:45.500 --> 00:00:49.130 Why should we be concerned about this Charles River? 00:00:53.840 --> 00:00:54.340 Yes? 00:00:54.340 --> 00:00:56.290 Because we live next to it. 00:00:56.290 --> 00:00:58.900 Because we live-- that's a good reason. 00:00:58.900 --> 00:01:00.430 Because we live next to it. 00:01:00.430 --> 00:01:01.300 Anyone else? 00:01:04.150 --> 00:01:05.100 Aisha? 00:01:05.100 --> 00:01:06.985 AUDIENCE: To care about your environment. 00:01:06.985 --> 00:01:08.860 JOHN DOLHUN: You care about your environment. 00:01:08.860 --> 00:01:14.080 And speaking of caring about your environment, 00:01:14.080 --> 00:01:18.130 we've got some problems with phosphate out there. 00:01:18.130 --> 00:01:27.990 We've got high phosphorus concentrations. 00:01:27.990 --> 00:01:30.420 And those high phosphorus concentrations 00:01:30.420 --> 00:01:34.020 lead to algal blooms. 00:01:41.230 --> 00:01:56.125 And those algal blooms produce toxic chemicals and odors. 00:02:00.610 --> 00:02:06.040 And when all this algae dies, it heads down to the bottom 00:02:06.040 --> 00:02:10.980 and breaks off and it's acted on by decomposers. 00:02:10.980 --> 00:02:14.350 These microbes start to chew it apart 00:02:14.350 --> 00:02:19.510 and they use up the dissolved oxygen so that we get lower-- 00:02:26.240 --> 00:02:29.780 lower dissolved oxygen in the water. 00:02:29.780 --> 00:02:33.505 And what that does is it leads to fish kills. 00:02:40.990 --> 00:02:43.720 And our recreational ability is impaired. 00:03:02.660 --> 00:03:06.890 So here are some examples of what I'm talking about. 00:03:06.890 --> 00:03:10.150 This is Florida, 2016. 00:03:10.150 --> 00:03:14.380 This is Lake Okeechobee, one of the largest fresh water lakes 00:03:14.380 --> 00:03:15.620 in Florida. 00:03:15.620 --> 00:03:19.540 This is a 30 mile long fish kill. 00:03:19.540 --> 00:03:23.890 It involves some 50 species of fish. 00:03:23.890 --> 00:03:27.760 The cause, most probably, an algal bloom, 00:03:27.760 --> 00:03:31.960 the result of leaking septic systems, 00:03:31.960 --> 00:03:36.250 fertilizers from lawns going into the water. 00:03:36.250 --> 00:03:38.390 This is an economic disaster. 00:03:38.390 --> 00:03:42.100 It's going to take decades to recover from this. 00:03:42.100 --> 00:03:44.860 Is Bradenton, Florida, 2018. 00:03:44.860 --> 00:03:49.650 This is their harbor filled with dead fish. 00:03:49.650 --> 00:03:54.870 This started from an algal bloom that turned into a red tide. 00:03:54.870 --> 00:03:58.440 And the red tide stretched about 150 miles 00:03:58.440 --> 00:04:02.040 off the coast of Florida, and gradually, 00:04:02.040 --> 00:04:05.850 the wind and the currents brought it into shore. 00:04:05.850 --> 00:04:07.950 And when that red tide came in to shore, 00:04:07.950 --> 00:04:12.450 it started releasing toxins into the air and water, 00:04:12.450 --> 00:04:17.459 and then the nutrients broke off and microbes 00:04:17.459 --> 00:04:20.339 started digesting them and used up the oxygen, 00:04:20.339 --> 00:04:23.110 and all these fish died. 00:04:23.110 --> 00:04:26.740 This is Australia, 2019. 00:04:26.740 --> 00:04:30.970 This is the Darling River, but it also happened in 00:04:30.970 --> 00:04:32.230 the [INAUDIBLE] River. 00:04:32.230 --> 00:04:36.040 And they had a successive run of these fish kills, 00:04:36.040 --> 00:04:38.420 one right after the other. 00:04:38.420 --> 00:04:41.590 Again, it's global hot temperatures 00:04:41.590 --> 00:04:45.710 and agricultural runoff. 00:04:45.710 --> 00:04:50.090 This is the Charles River, August, 2019. 00:04:50.090 --> 00:04:52.850 This is the largest algal bloom, I think, 00:04:52.850 --> 00:04:54.770 that we've had out there. 00:04:54.770 --> 00:04:57.770 It actually stretched from the BU bridge 00:04:57.770 --> 00:05:00.110 to the Museum of Science. 00:05:00.110 --> 00:05:03.290 And cyanobacteria was detected. 00:05:03.290 --> 00:05:07.690 This is a health problem. 00:05:07.690 --> 00:05:12.890 So we're going to be measuring phosphorus in the waters 00:05:12.890 --> 00:05:13.470 out here. 00:05:13.470 --> 00:05:15.600 That's one of the things we're going to do. 00:05:15.600 --> 00:05:18.320 And there are two types of phosphorus, 00:05:18.320 --> 00:05:23.660 there's the inorganic, which is simply 00:05:23.660 --> 00:05:26.450 salts of phosphoric acid, and then 00:05:26.450 --> 00:05:29.060 if you create esters of the inorganic form, 00:05:29.060 --> 00:05:32.390 you have the organic form of phosphate. 00:05:36.380 --> 00:05:38.150 So let's take a look for a moment 00:05:38.150 --> 00:05:41.150 at the inorganic phosphate. 00:05:41.150 --> 00:05:45.320 I mean, phosphorus is like, the 11th most abundant element 00:05:45.320 --> 00:05:47.280 on the planet. 00:05:47.280 --> 00:05:50.330 And it's not found in elemental form. 00:05:50.330 --> 00:05:55.230 You won't find any pure phosphorous anywhere 00:05:55.230 --> 00:05:56.490 on the Earth. 00:05:56.490 --> 00:06:01.470 It's found in these types of phosphates, in rocks and soils, 00:06:01.470 --> 00:06:04.390 and that's how it exists. 00:06:04.390 --> 00:06:09.060 So the main inorganic player here is the orthophosphate. 00:06:16.800 --> 00:06:20.580 And that's the PO4 to the 3 minus. 00:06:20.580 --> 00:06:24.900 This is the most stable form of phosphorus. 00:06:24.900 --> 00:06:29.460 And this is the form that's readily available to plants 00:06:29.460 --> 00:06:31.800 for uptake by the plants. 00:06:31.800 --> 00:06:37.470 I mean, all plants and animals need phosphorus for growth. 00:06:37.470 --> 00:06:43.050 It's the backbone of our DNA and the Krebs cycle. 00:06:43.050 --> 00:06:44.940 Plants need it in photosynthesis. 00:06:44.940 --> 00:06:47.340 They have to extract it from their environment 00:06:47.340 --> 00:06:50.280 because they're not going to make sugar unless they first 00:06:50.280 --> 00:06:54.540 make ATP to actually connect those bonds in the sugars 00:06:54.540 --> 00:06:58.060 that they're making. 00:06:58.060 --> 00:07:01.590 So we've got this orthophosphate, the main player 00:07:01.590 --> 00:07:04.800 here, but in the inorganic category, 00:07:04.800 --> 00:07:06.720 you can actually connect several of these 00:07:06.720 --> 00:07:09.780 together and form a polyphosphate, 00:07:09.780 --> 00:07:11.460 such as our detergents. 00:07:11.460 --> 00:07:14.580 A lot of detergents are polyphosphates. 00:07:14.580 --> 00:07:21.150 P3O10 to the 5 minus would be a polyphosphate. 00:07:21.150 --> 00:07:23.460 The interesting thing about the polyphosphates 00:07:23.460 --> 00:07:29.400 is as soon as they hit the water, 00:07:29.400 --> 00:07:32.480 they hydrolyze into the orthophosphate. 00:07:43.840 --> 00:07:48.400 And then we've got the organic phosphates, 00:07:48.400 --> 00:07:51.520 which are esters of the inorganic form. 00:07:51.520 --> 00:07:58.370 And organic phosphates are found in all living tissues. 00:07:58.370 --> 00:08:06.870 So all living tissues, both plants and animals, 00:08:06.870 --> 00:08:09.690 have organic phosphates. 00:08:09.690 --> 00:08:15.630 And waste is also another form of the organic phosphates. 00:08:21.100 --> 00:08:26.290 So when something living dies, it starts to decay. 00:08:26.290 --> 00:08:31.060 What happens is the phosphates actually 00:08:31.060 --> 00:08:34.510 convert to the orthophosphate. 00:08:34.510 --> 00:08:37.970 That's what happens to them. 00:08:37.970 --> 00:08:40.450 So this is what we're going to be measuring. 00:08:40.450 --> 00:08:44.860 And now, I'd like to talk for a few minutes about how 00:08:44.860 --> 00:08:49.440 it gets into the water, where all this stuff is coming from. 00:08:49.440 --> 00:08:52.100 So we're going to look at some of the primary sources 00:08:52.100 --> 00:08:53.690 of the phosphorus. 00:08:58.740 --> 00:09:00.570 The first one is storm water runoff. 00:09:10.610 --> 00:09:17.810 Can anyone give me an example of some phosphoruses, phosphates 00:09:17.810 --> 00:09:20.285 that can get into the water from storm water runoff? 00:09:28.490 --> 00:09:29.307 Yes, Aisha. 00:09:29.307 --> 00:09:33.590 AUDIENCE: I'm not sure if there's a phosphate in dirt. 00:09:33.590 --> 00:09:34.590 JOHN DOLHUN: Absolutely. 00:09:34.590 --> 00:09:36.360 There's phosphate in the dirt. 00:09:36.360 --> 00:09:39.420 And that would get washed in. 00:09:39.420 --> 00:09:42.090 What else? 00:09:42.090 --> 00:09:43.670 Yes, Jimmy? 00:09:43.670 --> 00:09:46.460 AUDIENCE: Probably less here, but in agriculture, 00:09:46.460 --> 00:09:48.375 I'm pretty sure they're used in fertilizer. 00:09:48.375 --> 00:09:49.500 JOHN DOLHUN: Oh, gosh, yes. 00:09:49.500 --> 00:09:53.280 Fertilizers are a big thing because of lawns. 00:09:53.280 --> 00:10:00.920 So we've got soil here and fertilizers. 00:10:08.490 --> 00:10:11.670 Anything else? 00:10:11.670 --> 00:10:12.946 Jimmy? 00:10:12.946 --> 00:10:15.360 AUDIENCE: I guess animal droppings? 00:10:15.360 --> 00:10:16.530 JOHN DOLHUN: Absolutely. 00:10:16.530 --> 00:10:17.700 Animal waste. 00:10:17.700 --> 00:10:21.300 I mean, think about where do they put pig farms? 00:10:21.300 --> 00:10:24.940 They put them all by a river, right? 00:10:24.940 --> 00:10:30.720 And all those geese, the guano, droppings, everything, they're 00:10:30.720 --> 00:10:32.070 all out there by the river. 00:10:32.070 --> 00:10:35.190 And all that stuff is being washed in. 00:10:35.190 --> 00:10:38.520 So animal waste is a big, big source here. 00:10:46.790 --> 00:10:47.720 Anything else? 00:10:53.670 --> 00:10:57.270 You ever got your car washed in a car wash? 00:10:57.270 --> 00:10:59.610 Do you ever sit in it while you're going through, 00:10:59.610 --> 00:11:01.890 see all that soap coming down? 00:11:01.890 --> 00:11:03.330 Tons of soap. 00:11:03.330 --> 00:11:05.910 And all that soap's going into the sewer systems, 00:11:05.910 --> 00:11:12.300 and when it starts to rain, heavy rains, it bubbles over. 00:11:12.300 --> 00:11:14.700 So car washes would be a big source, 00:11:14.700 --> 00:11:17.130 and there's your polyphosphates. 00:11:23.130 --> 00:11:25.680 Another one that you might not be as familiar with 00:11:25.680 --> 00:11:26.565 is car exhausts. 00:11:35.460 --> 00:11:39.600 Car exhausts have a catalyst tube in there. 00:11:39.600 --> 00:11:44.800 When that tube gets hot, like 500, 600, 700 degrees, 00:11:44.800 --> 00:11:48.570 it can form cerium phosphate, which is released 00:11:48.570 --> 00:11:51.420 in the exhaust effluent. 00:11:51.420 --> 00:11:54.450 So cerium phosphate would be a culprit here. 00:11:58.560 --> 00:12:02.730 And then probably the biggest source 00:12:02.730 --> 00:12:07.050 is discharge from wastewater treatment plants. 00:12:07.050 --> 00:12:12.830 Did any of you ever go to tour a wastewater treatment plant? 00:12:12.830 --> 00:12:15.120 Anyone? 00:12:15.120 --> 00:12:17.370 Oh, you did? 00:12:17.370 --> 00:12:18.600 Kelly, right? 00:12:18.600 --> 00:12:20.340 Could you tell us-- tell us about it, 00:12:20.340 --> 00:12:22.410 what your experience was? 00:12:22.410 --> 00:12:24.900 AUDIENCE: It was a school fieldtrip a long time ago, 00:12:24.900 --> 00:12:26.730 I think. 00:12:26.730 --> 00:12:27.800 It was interesting. 00:12:27.800 --> 00:12:29.768 So they purified or treat the water 00:12:29.768 --> 00:12:31.244 with several different methods. 00:12:31.244 --> 00:12:33.400 On of them was just like, bacterial, 00:12:33.400 --> 00:12:35.644 and then they introduce it [INAUDIBLE].. 00:12:35.644 --> 00:12:37.770 JOHN DOLHUN: Yeah, they aerate it with bacteria, 00:12:37.770 --> 00:12:40.980 I think, in the secondary treatment. 00:12:40.980 --> 00:12:45.810 And they do that to get rid of organic matter 00:12:45.810 --> 00:12:48.270 or to digest it down to sludge. 00:12:48.270 --> 00:12:49.140 AUDIENCE: Yeah. 00:12:49.140 --> 00:12:51.692 And then there's a UV method. 00:12:51.692 --> 00:12:52.650 JOHN DOLHUN: Very good. 00:12:52.650 --> 00:12:55.920 I mean, the most modern plants have this ultraviolet rays 00:12:55.920 --> 00:12:57.270 at the very end. 00:12:57.270 --> 00:13:01.350 You can walk along and you can see a glass floor. 00:13:01.350 --> 00:13:03.450 You can see the water going through 00:13:03.450 --> 00:13:05.940 with the ultraviolet rays hitting it. 00:13:05.940 --> 00:13:09.870 And then, at the end, they have a faucet 00:13:09.870 --> 00:13:13.110 and they offer you a drink. 00:13:13.110 --> 00:13:15.780 I mean, there was no one in my group 00:13:15.780 --> 00:13:19.710 that availed themself to take a sip of that water 00:13:19.710 --> 00:13:22.080 after going through that. 00:13:22.080 --> 00:13:25.200 But let's put this in perspective. 00:13:25.200 --> 00:13:36.540 So wastewater treatment plants, they're 00:13:36.540 --> 00:13:40.020 all built along rivers or oceans. 00:13:40.020 --> 00:13:45.960 And when a heavy rain, they start to discharge. 00:13:45.960 --> 00:13:47.040 They have to discharge. 00:13:47.040 --> 00:13:48.750 They can't take the flow. 00:13:48.750 --> 00:13:50.880 First thing, they may discharge some 00:13:50.880 --> 00:13:53.280 of the secondary treated water. 00:13:53.280 --> 00:13:56.550 Sometimes, they have to discharge the raw sewage. 00:13:56.550 --> 00:13:59.850 But to put it in perspective, all of us 00:13:59.850 --> 00:14:08.640 produce about 2.2 grams of pee per day. 00:14:08.640 --> 00:14:11.970 I'm talking about phosphorus here. 00:14:11.970 --> 00:14:16.980 That's about 1.8 pounds per year. 00:14:19.720 --> 00:14:23.370 Now, when that phosphorus hits the sewage treatment plant, 00:14:23.370 --> 00:14:27.090 it's in the effluent, it gets diluted down. 00:14:27.090 --> 00:14:29.400 You're talking somewhere between 2 00:14:29.400 --> 00:14:40.410 and probably 20 milligrams per liter PPM of phosphorous 00:14:40.410 --> 00:14:42.720 in the water. 00:14:42.720 --> 00:14:46.050 After the secondary treatment, they only 00:14:46.050 --> 00:14:52.120 take out between 1 and 2 milligrams per liter. 00:14:52.120 --> 00:14:57.060 So you end up with a large excess of phosphorus 00:14:57.060 --> 00:14:59.770 in the treated water. 00:14:59.770 --> 00:15:03.720 So when they release, it's a ton of phosphorus 00:15:03.720 --> 00:15:05.550 hitting the water. 00:15:05.550 --> 00:15:07.890 But the good news is-- 00:15:07.890 --> 00:15:15.870 I'm going to draw a smiley face here, because the EPA just 00:15:15.870 --> 00:15:18.390 filed a regulation forcing-- 00:15:18.390 --> 00:15:21.180 they're going to force all these wastewater treatment 00:15:21.180 --> 00:15:26.197 plants to cut back, get rid of the phosphorus in the water, 00:15:26.197 --> 00:15:27.780 and they're going to have to-- they're 00:15:27.780 --> 00:15:30.330 going to have to take it down to less 00:15:30.330 --> 00:15:35.230 than 1.0 milligrams per liter. 00:15:35.230 --> 00:15:38.460 So all these plants are running around now trying to figure out 00:15:38.460 --> 00:15:39.960 how they're going to do that. 00:15:39.960 --> 00:15:42.990 This, I believe, just went into effect this year, 00:15:42.990 --> 00:15:47.490 and may go-- may be starting in January of 2020, 00:15:47.490 --> 00:15:52.290 but there are EPA regulations that are just coming out. 00:15:52.290 --> 00:15:55.590 The other major source is sewer overflows. 00:15:55.590 --> 00:15:59.040 And in New England, everyone-- 00:15:59.040 --> 00:16:03.730 it's notorious that you have a sump pump in your basement. 00:16:03.730 --> 00:16:07.710 So when your basement floods, the pump starts up 00:16:07.710 --> 00:16:08.880 and it pumps everything. 00:16:08.880 --> 00:16:11.080 They're connected to the sewer systems. 00:16:11.080 --> 00:16:12.960 So everything in the kitchen sink 00:16:12.960 --> 00:16:17.400 is going into the sewer system and it's bubbling over. 00:16:17.400 --> 00:16:20.260 So those are the primary sources. 00:16:20.260 --> 00:16:24.660 Now, let's look at the ecological effect 00:16:24.660 --> 00:16:27.420 of all this phosphorus. 00:16:27.420 --> 00:16:30.930 This is the Charles River, the famous Charles River. 00:16:30.930 --> 00:16:33.360 This is up by Newton, Mass. 00:16:33.360 --> 00:16:37.170 There's a guy in a canoe trying to pull out the vegetation 00:16:37.170 --> 00:16:39.600 out of the water. 00:16:39.600 --> 00:16:42.880 What this vegetation does is two things. 00:16:42.880 --> 00:16:46.920 First, it's blocking the sunlight 00:16:46.920 --> 00:16:51.540 to organisms and other plants down below the surface that 00:16:51.540 --> 00:16:52.920 need that sun. 00:16:52.920 --> 00:16:57.270 And the second thing is it's going to die and produce 00:16:57.270 --> 00:17:01.560 these swamp-like odors, and then it's 00:17:01.560 --> 00:17:04.800 going to get decomposed by microorganisms that 00:17:04.800 --> 00:17:07.599 are going to use up the oxygen. 00:17:07.599 --> 00:17:11.039 This is the result. This is blue-green algae. 00:17:14.440 --> 00:17:19.060 This is really-- another name for this is cyanobacteria. 00:17:19.060 --> 00:17:22.839 It's the cyanobacteria that give it that green color 00:17:22.839 --> 00:17:24.329 on the surface of the water. 00:17:27.050 --> 00:17:29.660 Here are some other forms of it. 00:17:29.660 --> 00:17:33.140 You can get this pea soup kind of look, 00:17:33.140 --> 00:17:35.900 or you can get this mossy look, or you 00:17:35.900 --> 00:17:38.240 might get a painted look. 00:17:38.240 --> 00:17:42.470 The bottom line is it's all bacteria. 00:17:42.470 --> 00:17:45.350 It's unicellular bacteria. 00:17:45.350 --> 00:17:47.600 These are prokaryotic bacteria. 00:17:47.600 --> 00:17:51.140 They have no nucleus, but they make their own food 00:17:51.140 --> 00:17:54.780 and they secrete chemicals. 00:17:54.780 --> 00:17:57.990 These are the same bacteria, believe it or not, 00:17:57.990 --> 00:18:02.530 that gave us life 3.5 billion years ago. 00:18:02.530 --> 00:18:04.500 And now, they're out to get us. 00:18:04.500 --> 00:18:06.990 Isn't that amazing? 00:18:06.990 --> 00:18:10.300 Every time I look at this, I can't believe it. 00:18:10.300 --> 00:18:12.120 I mean, when we had no oxygen, these 00:18:12.120 --> 00:18:14.850 were the guys that were giving our oxygen atmosphere, 00:18:14.850 --> 00:18:17.820 and now, look what they're doing. 00:18:17.820 --> 00:18:22.540 Now, if these are out there in the water, 00:18:22.540 --> 00:18:24.210 you don't want to go in the water. 00:18:24.210 --> 00:18:28.950 If you do, you are dead meat, and I'll tell you why. 00:18:28.950 --> 00:18:30.930 You can have all kinds of symptoms, 00:18:30.930 --> 00:18:33.900 you can get covered with a rash, you 00:18:33.900 --> 00:18:38.430 can have diarrhea, flu-like symptoms, eye and ear problems, 00:18:38.430 --> 00:18:41.070 respiratory problems. 00:18:41.070 --> 00:18:44.610 I gave you an article in the news. 00:18:44.610 --> 00:18:46.770 This is The New York Times. 00:18:46.770 --> 00:18:51.180 Central Park in New York, all of their ponds, 00:18:51.180 --> 00:18:53.730 infected with blue-green algae. 00:18:57.400 --> 00:18:58.940 Here's a good example. 00:18:58.940 --> 00:19:02.860 This is today, "Ohio strikes a Blow in Algae Fight." 00:19:02.860 --> 00:19:05.590 This is The Wall Street Journal this morning. 00:19:05.590 --> 00:19:08.020 This article just came out. 00:19:08.020 --> 00:19:12.680 Interestingly, Ohio had this algae problem 10 years ago, 00:19:12.680 --> 00:19:14.650 and they took around one of their lakes 00:19:14.650 --> 00:19:19.990 and they built up these wetland areas 00:19:19.990 --> 00:19:22.840 to prevent the runoff from reaching-- 00:19:22.840 --> 00:19:25.120 the agricultural runoff from reaching the lake, 00:19:25.120 --> 00:19:27.460 and it's actually working. 00:19:27.460 --> 00:19:30.490 So there are ideas out there that you 00:19:30.490 --> 00:19:32.605 can come up with an idea and solve a problem. 00:19:38.680 --> 00:19:41.850 So some of these cyanobacteria, some of the fresh water 00:19:41.850 --> 00:19:46.050 bacteria produce very toxic chemicals. 00:19:46.050 --> 00:19:50.070 One form of these are the microcystins. 00:19:50.070 --> 00:19:53.910 There are something like 50 different micocystins that 00:19:53.910 --> 00:19:56.220 have been identified to date. 00:19:56.220 --> 00:19:59.320 It's a cyclic peptide here. 00:19:59.320 --> 00:20:01.950 And this is a hepatotoxin. 00:20:01.950 --> 00:20:06.310 So once this gets through your skin into your body, 00:20:06.310 --> 00:20:09.660 your liver is going to get attacked, 00:20:09.660 --> 00:20:11.850 and you're pretty much gone. 00:20:11.850 --> 00:20:14.080 There's not much you can do about it. 00:20:14.080 --> 00:20:16.020 The article mentions the dogs-- 00:20:16.020 --> 00:20:19.480 one woman had three dogs in North Carolina. 00:20:19.480 --> 00:20:21.840 She let them go for a swim in a pond. 00:20:21.840 --> 00:20:25.860 All three dogs died within a few hours. 00:20:25.860 --> 00:20:28.670 So this is really nasty stuff. 00:20:28.670 --> 00:20:33.020 And I challenge you to think about coming up 00:20:33.020 --> 00:20:34.400 with an antidote for this. 00:20:36.960 --> 00:20:39.090 There's your startup company right here. 00:20:39.090 --> 00:20:40.290 I'm giving it to you. 00:20:43.890 --> 00:20:47.220 When this stuff is active, you go out to the Charles River, 00:20:47.220 --> 00:20:50.700 you'll see these signs posted warning people and pets 00:20:50.700 --> 00:20:52.460 to stay out of the water. 00:20:55.950 --> 00:20:57.310 Here's another example. 00:20:57.310 --> 00:21:00.720 This is the summer of 2014. 00:21:00.720 --> 00:21:04.440 This is a satellite picture of Lake Erie, one 00:21:04.440 --> 00:21:07.680 of the five Great Lakes in this country. 00:21:07.680 --> 00:21:13.170 And the lake actually borders Canada on one side, separates 00:21:13.170 --> 00:21:16.320 Canada from the US near Ontario, and then there 00:21:16.320 --> 00:21:20.250 are several states that border the lake. 00:21:20.250 --> 00:21:25.380 Out here to the west is Toledo, Ohio, and Toledo, 00:21:25.380 --> 00:21:28.260 fourth largest city in Ohio, has a population 00:21:28.260 --> 00:21:30.570 of about a half million. 00:21:30.570 --> 00:21:35.130 This was their tap water in 2014. 00:21:35.130 --> 00:21:40.590 And I had a 5.310 student in class four years ago who 00:21:40.590 --> 00:21:43.200 remembers this. 00:21:43.200 --> 00:21:46.380 I mean, this is serious business. 00:21:46.380 --> 00:21:48.580 And it's happening all over, all over the world. 00:21:51.230 --> 00:21:52.280 Here's another picture. 00:21:52.280 --> 00:21:58.710 This is the largest landlocked body of water on the Earth. 00:21:58.710 --> 00:22:01.290 Anybody from Europe here recognize this? 00:22:07.440 --> 00:22:07.940 What? 00:22:07.940 --> 00:22:09.350 Who said that? 00:22:09.350 --> 00:22:12.710 Yes, Sean, exactly correct, that's the Caspian Sea. 00:22:12.710 --> 00:22:14.750 It's bordered by five countries. 00:22:14.750 --> 00:22:19.670 But look at the massive, massive algal growth 00:22:19.670 --> 00:22:21.410 from this satellite picture. 00:22:21.410 --> 00:22:26.030 Here's the Volga River, Europe's longest river, pouring into it. 00:22:26.030 --> 00:22:29.250 It's a 2,000 mile long river. 00:22:29.250 --> 00:22:33.870 Here's a new word for you, eutrophication. 00:22:33.870 --> 00:22:37.220 It's from the Greek meaning well nourished. 00:22:40.580 --> 00:22:45.410 So how much phosphorus is acceptable? 00:22:45.410 --> 00:22:48.530 The EPA came out in 2000-- 00:22:48.530 --> 00:22:50.930 that was almost 20 years ago-- 00:22:50.930 --> 00:22:55.760 and said 0.0238 milligrams per liter. 00:22:55.760 --> 00:23:00.230 Well, we know today that if you have anything 00:23:00.230 --> 00:23:09.530 greater than or equal to 0.016 milligrams per liter, 00:23:09.530 --> 00:23:15.260 you're going to have really a large algal growth 00:23:15.260 --> 00:23:18.890 proliferating in your water. 00:23:18.890 --> 00:23:23.590 Now, these concentrations of phosphorus, they're low. 00:23:23.590 --> 00:23:26.890 And it's going to be challenging to measure those. 00:23:26.890 --> 00:23:29.150 This is what we're going to do. 00:23:29.150 --> 00:23:31.390 The other thing that makes it challenging 00:23:31.390 --> 00:23:38.690 is phosphates are colorless. 00:23:38.690 --> 00:23:41.630 So how are we going to use UV vis to measure 00:23:41.630 --> 00:23:43.040 these concentrations? 00:23:46.700 --> 00:23:47.890 Anybody have an idea? 00:23:57.310 --> 00:23:58.480 Yes? 00:23:58.480 --> 00:24:01.240 Maybe we can react them with something 00:24:01.240 --> 00:24:03.090 that will make them colorful? 00:24:03.090 --> 00:24:05.340 Maybe we can react them with something 00:24:05.340 --> 00:24:06.570 that can make them colorful. 00:24:06.570 --> 00:24:08.040 Very good. 00:24:08.040 --> 00:24:09.000 Very good. 00:24:09.000 --> 00:24:11.220 Yeah, I like that. 00:24:11.220 --> 00:24:12.650 Keisha, right? 00:24:12.650 --> 00:24:14.865 AUDIENCE: Gizelle. 00:24:14.865 --> 00:24:15.740 JOHN DOLHUN: Gizelle. 00:24:15.740 --> 00:24:17.270 I'm sorry, Gizelle. 00:24:17.270 --> 00:24:18.810 Where's Keisha? 00:24:18.810 --> 00:24:19.670 There she is. 00:24:19.670 --> 00:24:20.960 OK. 00:24:20.960 --> 00:24:23.540 All right, so react them with something 00:24:23.540 --> 00:24:26.180 that makes it colorful. 00:24:26.180 --> 00:24:30.410 So here comes chemistry to the rescue, right? 00:24:30.410 --> 00:24:34.280 So phosphates are very reactive. 00:24:34.280 --> 00:24:39.560 So we can actually take river water and this method here, 00:24:39.560 --> 00:24:42.590 this is the ammonium metavanadate method. 00:24:42.590 --> 00:24:48.320 When I tried to develop this Charles River water testing, 00:24:48.320 --> 00:24:50.660 I started with this method because it 00:24:50.660 --> 00:24:54.440 was written up as the method to detect phosphorus 00:24:54.440 --> 00:24:56.000 in river water. 00:24:56.000 --> 00:24:57.860 So you would take the river water, 00:24:57.860 --> 00:25:01.850 mix it with molybdate, ammonium metavanadate, 00:25:01.850 --> 00:25:07.340 and you create this color heteropoly molybdic acid 00:25:07.340 --> 00:25:10.250 that has a yellow color and it absorbs light 00:25:10.250 --> 00:25:14.240 at 400 nanometers. 00:25:14.240 --> 00:25:19.160 What I found is that this method was not sensitive enough 00:25:19.160 --> 00:25:21.980 to actually measure the phosphorus 00:25:21.980 --> 00:25:25.130 levels in the Charles River. 00:25:25.130 --> 00:25:28.700 It's a great method for measuring phosphorus in sewage, 00:25:28.700 --> 00:25:30.560 but not the rivers. 00:25:30.560 --> 00:25:32.690 So I looked around and I found what's 00:25:32.690 --> 00:25:38.120 called the ascorbic acid method, an EPA-approved method where 00:25:38.120 --> 00:25:43.340 you actually took river water, mixed it 00:25:43.340 --> 00:25:47.210 with molybdate, sulfuric acid, and you 00:25:47.210 --> 00:25:53.090 create this heteropoly molybdic acid, which is colorless. 00:25:53.090 --> 00:25:59.090 But the good thing is this heteropoly molybdate anion 00:25:59.090 --> 00:26:03.260 can accept electrons and be reduced down 00:26:03.260 --> 00:26:07.620 and ascorbic acid can cause that reduction. 00:26:07.620 --> 00:26:11.600 And you end up getting this molybdenum blue complex, 00:26:11.600 --> 00:26:14.810 a mixed valence complex that absorbs light 00:26:14.810 --> 00:26:19.630 at 880 nanometers. 00:26:19.630 --> 00:26:22.450 So this is great because the concentration 00:26:22.450 --> 00:26:25.450 of the phosphorus in the complexes 00:26:25.450 --> 00:26:27.340 is proportional to the absorbance 00:26:27.340 --> 00:26:30.620 of the light in these things. 00:26:30.620 --> 00:26:34.060 So this is what you're actually making. 00:26:34.060 --> 00:26:35.020 It's beautiful. 00:26:35.020 --> 00:26:36.970 This is a Keggin structure. 00:26:36.970 --> 00:26:41.770 It captures the phosphorus in the center, surrounded by 12 00:26:41.770 --> 00:26:45.790 molybdenums and 40 oxygens. 00:26:45.790 --> 00:26:49.360 I want you to take a moment and look at this. 00:26:49.360 --> 00:26:52.120 And I'd like you all to close your eyes for a moment 00:26:52.120 --> 00:26:54.490 and think about this image. 00:26:54.490 --> 00:26:55.390 Close your eyes. 00:27:02.260 --> 00:27:05.770 OK, open your eyes, please. 00:27:05.770 --> 00:27:09.010 I want you to carry this image with you 00:27:09.010 --> 00:27:13.690 into the lab when you do this experiment. 00:27:13.690 --> 00:27:17.280 You're actually going to be making this in your beakers 00:27:17.280 --> 00:27:21.330 when you add the color developer to your water samples. 00:27:21.330 --> 00:27:26.310 You're creating this in about 15 minutes in your beaker. 00:27:26.310 --> 00:27:28.695 This is inorganic chemistry at its best. 00:27:31.490 --> 00:27:36.410 Now, I want to spend the next several slides showing you 00:27:36.410 --> 00:27:39.080 how we're going to actually measure 00:27:39.080 --> 00:27:43.080 the concentrations of this. 00:27:43.080 --> 00:27:47.240 So we're going to be shining electromagnetic energy 00:27:47.240 --> 00:27:49.710 on a sample. 00:27:49.710 --> 00:27:52.640 And if you look at the visible light 00:27:52.640 --> 00:27:57.020 here that I broke out of this electromagnetic spectrum, 00:27:57.020 --> 00:28:01.100 on the red end of this, we're going 00:28:01.100 --> 00:28:04.760 to be looking at our samples on that far red end 00:28:04.760 --> 00:28:07.010 in the near IR. 00:28:07.010 --> 00:28:08.720 So that's where you're going to be-- 00:28:08.720 --> 00:28:10.670 where you're going to be taking your readings. 00:28:10.670 --> 00:28:15.585 Now, what can happen when you shine radiation on your sample? 00:28:15.585 --> 00:28:16.085 Anyone? 00:28:19.590 --> 00:28:20.655 Yes, Kim. 00:28:20.655 --> 00:28:24.904 AUDIENCE: Photobleaching 00:28:24.904 --> 00:28:25.696 JOHN DOLHUN: Sorry? 00:28:25.696 --> 00:28:28.080 AUDIENCE: Some of your sample could get photobleached. 00:28:28.080 --> 00:28:30.840 JOHN DOLHUN: Some of your sample could get photobleached, yeah. 00:28:30.840 --> 00:28:33.020 That's a possibility. 00:28:33.020 --> 00:28:35.910 What else? 00:28:35.910 --> 00:28:36.410 Yes? 00:28:36.410 --> 00:28:39.679 AUDIENCE: [INAUDIBLE] 00:28:43.420 --> 00:28:44.480 JOHN DOLHUN: Exactly. 00:28:44.480 --> 00:28:46.600 I mean, electrons could get chewed up 00:28:46.600 --> 00:28:48.490 to a higher energy levels. 00:28:48.490 --> 00:28:51.190 Little nuclei could see that happen and get nervous 00:28:51.190 --> 00:28:53.320 and start to rearrange themselves. 00:28:53.320 --> 00:28:56.980 And the molecule, as Kelly said, could burst into vibration. 00:28:56.980 --> 00:29:06.030 And your UV is actually monitoring 00:29:06.030 --> 00:29:08.850 all of those electronic transmissions 00:29:08.850 --> 00:29:12.570 that we can't see with our eye. 00:29:12.570 --> 00:29:17.980 And what the UV does is it draws you a smooth curve through all 00:29:17.980 --> 00:29:21.400 of those electronic transitions and you end up somewhere 00:29:21.400 --> 00:29:24.550 with your lambda max. 00:29:24.550 --> 00:29:28.390 What UV vis is, a good definition 00:29:28.390 --> 00:29:31.810 is it's just the interaction of light with matter 00:29:31.810 --> 00:29:33.991 as a function of wavelength. 00:29:37.760 --> 00:29:39.820 So here's your UV cuvette. 00:29:39.820 --> 00:29:43.040 Here's the radiation hitting that cuvette. 00:29:43.040 --> 00:29:45.640 What happens? 00:29:45.640 --> 00:29:47.583 What do you see up there happening? 00:29:53.270 --> 00:29:54.070 Yes, Ryan? 00:29:58.855 --> 00:30:00.070 Yeah, the lights focused. 00:30:00.070 --> 00:30:01.945 And what's happening to the sample? 00:30:11.080 --> 00:30:13.300 I'm sure it's heating up, yeah. 00:30:13.300 --> 00:30:14.570 Yes, Autumn? 00:30:14.570 --> 00:30:17.300 AUDIENCE: It absorbs sunlight and transmits sunlight and also 00:30:17.300 --> 00:30:17.800 re-emits. 00:30:20.190 --> 00:30:21.190 JOHN DOLHUN: Yeah, good. 00:30:21.190 --> 00:30:22.920 So some of the light's going through 00:30:22.920 --> 00:30:24.930 and some's getting absorbed. 00:30:24.930 --> 00:30:27.790 So let's look at that for a minute. 00:30:27.790 --> 00:30:31.920 So we've got absorbance minus the log 00:30:31.920 --> 00:30:36.180 of the transmitted light, which is i over i0. 00:30:38.895 --> 00:30:45.660 Now, absorbance is-- we're actually 00:30:45.660 --> 00:30:47.070 monitoring the absorbance. 00:30:47.070 --> 00:30:49.440 We're not monitoring the transmittance 00:30:49.440 --> 00:30:51.840 because absorbance is actually directly 00:30:51.840 --> 00:30:57.220 proportional to concentration by Beer's law. 00:30:57.220 --> 00:31:00.600 So we have this relationship. 00:31:00.600 --> 00:31:04.260 And E, the extinction coefficient, 00:31:04.260 --> 00:31:07.440 is the molar absorptivity constant, 00:31:07.440 --> 00:31:12.840 is simply the amount of light absorbed per unit 00:31:12.840 --> 00:31:17.140 concentration of your sample. 00:31:17.140 --> 00:31:18.840 Let me just rewrite this. 00:31:18.840 --> 00:31:20.500 Let me get rid of the logarithm. 00:31:20.500 --> 00:31:22.060 I want to show you something here. 00:31:22.060 --> 00:31:26.040 So I'm going to rewrite this. 00:31:35.140 --> 00:31:41.470 Let's actually graph the intensity 00:31:41.470 --> 00:31:45.180 of the incoming radiation here. 00:31:45.180 --> 00:31:56.090 We're going to graph that as a function of concentration. 00:31:56.090 --> 00:32:02.740 If you do that, you're going to see from that equation 00:32:02.740 --> 00:32:06.820 that the transmitted light decreases exponentially 00:32:06.820 --> 00:32:09.940 as the concentration increases. 00:32:09.940 --> 00:32:14.110 I want you to keep that in the back of your mind. 00:32:14.110 --> 00:32:16.450 This equation fascinated me. 00:32:16.450 --> 00:32:19.480 I like Beer's law. 00:32:19.480 --> 00:32:22.030 What this tells you, this extinction coefficient 00:32:22.030 --> 00:32:25.610 tells you, that it has to be a constant. 00:32:25.610 --> 00:32:27.970 So if you cut your concentration in half, 00:32:27.970 --> 00:32:30.710 absorption should be cut in half. 00:32:30.710 --> 00:32:32.390 So I wanted to prove this. 00:32:32.390 --> 00:32:35.590 So I went out and I made this compound, 00:32:35.590 --> 00:32:38.230 hexacyanoferrate(III). 00:32:38.230 --> 00:32:41.830 And I made up five solutions of this, 00:32:41.830 --> 00:32:45.440 and then I measured the absorbance of each solution. 00:32:45.440 --> 00:32:49.120 It absorbed light at 420 nanometers. 00:32:49.120 --> 00:32:53.505 And if you look here, 10 times e to the minus 4, 00:32:53.505 --> 00:32:58.600 if I cut that in half to 5 times e to the minus 4, indeed, 00:32:58.600 --> 00:33:02.900 the absorption gets cut in half as it should. 00:33:02.900 --> 00:33:07.690 So I graph this, got a nice, straight line. 00:33:07.690 --> 00:33:10.840 The change in absorption over the change in concentration 00:33:10.840 --> 00:33:11.980 is my slope. 00:33:11.980 --> 00:33:17.770 And it's 1,056.7 so that's my extinction coefficient. 00:33:17.770 --> 00:33:21.610 And this worked really well. 00:33:21.610 --> 00:33:24.670 But I want to caution you-- 00:33:24.670 --> 00:33:30.640 if you try this, and you're graphing absorption 00:33:30.640 --> 00:33:34.510 versus concentration, and you're doing Beer's law, 00:33:34.510 --> 00:33:36.820 you've got this nice, straight line, 00:33:36.820 --> 00:33:40.180 you might end up with something like this, 00:33:40.180 --> 00:33:43.600 where Beer's law falls apart. 00:33:43.600 --> 00:33:47.690 And it all comes back to this here-- 00:33:47.690 --> 00:33:49.790 the intensity of the transmitted light 00:33:49.790 --> 00:33:53.190 decreases exponentially with concentration. 00:33:53.190 --> 00:33:56.930 So eventually, if the concentration is too high 00:33:56.930 --> 00:34:01.400 your sample becomes saturated, and you're not 00:34:01.400 --> 00:34:04.310 going to be-- this Beer's law falls apart. 00:34:04.310 --> 00:34:06.530 I just want you to be aware of that. 00:34:06.530 --> 00:34:10.310 What I did is I made up all of my concentrations are very low. 00:34:10.310 --> 00:34:13.920 Beer's law worked fine. 00:34:13.920 --> 00:34:21.350 So now we're going to get to some serious business. 00:34:21.350 --> 00:34:25.230 This is what you have to do for this lab, for it to work. 00:34:25.230 --> 00:34:27.110 Otherwise, you will be a goner-- 00:34:27.110 --> 00:34:28.489 gonzo. 00:34:28.489 --> 00:34:31.719 You've got to clean this glassware. 00:34:31.719 --> 00:34:34.880 This is a list of the glassware that you'll need to clean. 00:34:34.880 --> 00:34:38.630 And you've got to do it with 10% hydrochloric acid, triple 00:34:38.630 --> 00:34:41.199 rinsed with Milli-Q Water. 00:34:41.199 --> 00:34:43.150 Why do you think you need to do that? 00:34:47.860 --> 00:34:48.949 Yes. 00:34:48.949 --> 00:34:51.580 AUDIENCE: Any contamination might change the products 00:34:51.580 --> 00:34:55.150 concentration. 00:34:55.150 --> 00:34:56.860 JOHN DOLHUN: Any contamination is going 00:34:56.860 --> 00:34:59.590 to just destroy the experiment. 00:34:59.590 --> 00:35:01.740 It's kind of like the Nano Building. 00:35:01.740 --> 00:35:05.260 You've seen them in there with their bunny suits on. 00:35:05.260 --> 00:35:10.060 One speck of dust, even a dander from your hair, 00:35:10.060 --> 00:35:13.510 is like a wrecking ball to the experiment. 00:35:13.510 --> 00:35:18.760 Well, one speck of phosphate from any detergent 00:35:18.760 --> 00:35:21.920 is going to wreck this experiment. 00:35:21.920 --> 00:35:24.340 So you've got to judiciously sit down. 00:35:24.340 --> 00:35:27.500 There'll be two of you-- you'll be partnered up for this. 00:35:27.500 --> 00:35:29.650 So you clean this up. 00:35:29.650 --> 00:35:33.310 And you'll do this on day two after the dissolved oxygen 00:35:33.310 --> 00:35:34.455 testing. 00:35:34.455 --> 00:35:35.830 This is what you're going to need 00:35:35.830 --> 00:35:38.860 for day three for the phosphate testing. 00:35:38.860 --> 00:35:42.070 So you can leave this glassware in the top drawer 00:35:42.070 --> 00:35:43.570 above your locker. 00:35:43.570 --> 00:35:45.070 It's not locked. 00:35:45.070 --> 00:35:47.020 And it'll be nice and ready for when 00:35:47.020 --> 00:35:50.570 you come in to do the testing. 00:35:50.570 --> 00:35:55.490 So this is what you have to do in this lab. 00:35:55.490 --> 00:35:58.780 First of all, we need to make up a set of standards 00:35:58.780 --> 00:36:00.670 that we can interpolate our river 00:36:00.670 --> 00:36:04.960 samples against to find the concentrations of the phosphate 00:36:04.960 --> 00:36:06.260 and phosphorus. 00:36:06.260 --> 00:36:08.710 So you're going to make seven standards up. 00:36:08.710 --> 00:36:13.240 And you're going to be using a stock solution. 00:36:16.580 --> 00:36:19.820 And the formula to use in all these tables 00:36:19.820 --> 00:36:23.900 is you're going to use this M1V1 equals M2V2. 00:36:27.810 --> 00:36:37.260 So if you have a 10 to the minus 1/3 molar stock solution, 00:36:37.260 --> 00:36:45.810 and you're taking 1 milliliter of it out, out of the bottle, 00:36:45.810 --> 00:36:48.255 how much molarity do you want to make 00:36:48.255 --> 00:36:53.850 to make up 100 mil solution? 00:36:53.850 --> 00:36:56.130 You'll be diluting this 1 mil to 100, 00:36:56.130 --> 00:36:59.400 and you'll see that your x is 10 to the minus 5. 00:36:59.400 --> 00:37:01.470 That's your stock solution of phosphate 00:37:01.470 --> 00:37:03.140 that you're going to create. 00:37:06.540 --> 00:37:09.300 So you just use that formula for all these. 00:37:09.300 --> 00:37:11.640 You're taking this much out of your 10 00:37:11.640 --> 00:37:14.220 to the minus 5 molar stock solution, 00:37:14.220 --> 00:37:16.800 and you're diluting it up to 10 mils. 00:37:16.800 --> 00:37:19.230 What's my concentration? 00:37:19.230 --> 00:37:20.730 Perfect. 00:37:20.730 --> 00:37:22.590 What you'll do is you'll come into the lab, 00:37:22.590 --> 00:37:25.170 and the TAs will go through this with you. 00:37:25.170 --> 00:37:27.990 You'll make up your stock solutions. 00:37:27.990 --> 00:37:31.410 And then you'll go to the river to get your water. 00:37:31.410 --> 00:37:36.690 And when you bring the water back to the lab, 00:37:36.690 --> 00:37:38.260 there'll be two of you. 00:37:38.260 --> 00:37:41.070 So one of you will go over to the hoods 00:37:41.070 --> 00:37:43.320 and get the color developer. 00:37:43.320 --> 00:37:47.190 And these are the four chemicals that we talked about 00:37:47.190 --> 00:37:48.930 in the color developer-- 00:37:48.930 --> 00:37:54.150 the ammonium molybdate, sulfuric acid, ascorbic acid, 00:37:54.150 --> 00:37:56.910 potassium antimonyl-tartrate. 00:37:56.910 --> 00:38:01.080 Potassium antimonyl-tartrate is there to actually speed up 00:38:01.080 --> 00:38:05.190 the reduction that's going on with ascorbic acid. 00:38:05.190 --> 00:38:07.110 That's important. 00:38:07.110 --> 00:38:11.460 If I didn't mention that before, that's the purpose of that. 00:38:11.460 --> 00:38:13.830 The ammonium molybdate, sulfuric acid, 00:38:13.830 --> 00:38:16.380 you're creating that Keggin structure, 00:38:16.380 --> 00:38:20.460 that heteropoly, colorless, molybdic acid. 00:38:20.460 --> 00:38:23.520 You also have to take this color developer in the order 00:38:23.520 --> 00:38:25.050 that it's written here. 00:38:25.050 --> 00:38:28.230 It'll be set up in burettes in the hood. 00:38:28.230 --> 00:38:31.620 If you, for example, take it in a wrong order, 00:38:31.620 --> 00:38:34.170 you could have a side reaction, and not 00:38:34.170 --> 00:38:39.280 get the color developer that you want to put in your sample. 00:38:39.280 --> 00:38:40.540 So it's important. 00:38:40.540 --> 00:38:43.860 So one of you will go to the hood, get the color developer. 00:38:43.860 --> 00:38:47.910 The other one will go to the river water you brought back, 00:38:47.910 --> 00:38:51.210 use a clean pipette, 10 mL pipette, 00:38:51.210 --> 00:38:55.095 and pipette five beakers with river water, five 00:38:55.095 --> 00:38:56.790 10-mL beakers. 00:38:56.790 --> 00:39:02.790 So you'll end up with 12-- seven standards and five samples. 00:39:02.790 --> 00:39:04.920 And then you add the color developer, 00:39:04.920 --> 00:39:10.240 and you wait 20 minutes, and you're ready to go. 00:39:10.240 --> 00:39:15.450 Just a couple other precautions that you should take-- 00:39:15.450 --> 00:39:18.020 we're going to be using 4-mL cuvettes. 00:39:18.020 --> 00:39:19.290 These are big inside. 00:39:19.290 --> 00:39:22.410 Don't use the 1 and 1/2 mL cuvettes. 00:39:22.410 --> 00:39:26.940 The other thing is all these cuvettes have a fill line. 00:39:26.940 --> 00:39:30.000 It becomes frosted at one point. 00:39:30.000 --> 00:39:33.900 And you want to stop pouring when you get to that line. 00:39:33.900 --> 00:39:35.490 You're going to take your beakers, 00:39:35.490 --> 00:39:37.620 and you're going to swirl them gently. 00:39:37.620 --> 00:39:39.720 And you're going to pour them by hand 00:39:39.720 --> 00:39:41.760 until you reach the fill line. 00:39:41.760 --> 00:39:43.410 Don't go beyond that. 00:39:43.410 --> 00:39:48.090 Also, all of these UV cuvettes have an arrow on one side. 00:39:48.090 --> 00:39:50.220 You want to be sure that the arrow is 00:39:50.220 --> 00:39:53.580 in the light beam when you put these cuvettes in the UV 00:39:53.580 --> 00:39:54.960 spectrometer. 00:39:54.960 --> 00:39:56.960 A lot of people have made mistakes, 00:39:56.960 --> 00:39:58.710 put them in the wrong way, and then you're 00:39:58.710 --> 00:40:01.080 not going to get very good readings. 00:40:01.080 --> 00:40:02.880 So the arrow's clear to see. 00:40:02.880 --> 00:40:05.790 What I usually do is arrange all my cuvettes 00:40:05.790 --> 00:40:07.770 in a box ahead of time. 00:40:07.770 --> 00:40:10.590 And then I pour my samples and put them in the box, 00:40:10.590 --> 00:40:12.970 and I know the arrow's in the right place. 00:40:12.970 --> 00:40:15.780 And when I go to the UV, I just lift them up and put them in. 00:40:18.300 --> 00:40:23.160 Also, keep in mind what Dr. Sarah Hewett told you 00:40:23.160 --> 00:40:27.120 the other day that there's two kinds of pipettes in the lab. 00:40:27.120 --> 00:40:29.910 This one is a blowout pipette. 00:40:29.910 --> 00:40:33.480 You've got to blow it all out to get your 10 mLs. 00:40:33.480 --> 00:40:36.660 This one is a to deliver pipette. 00:40:36.660 --> 00:40:38.430 You only go up to that last line. 00:40:38.430 --> 00:40:42.750 You don't blow the tip in, otherwise you put too much-- 00:40:42.750 --> 00:40:44.560 going to wreck your experiment. 00:40:44.560 --> 00:40:46.860 So make sure you look at the pipettes carefully. 00:40:49.880 --> 00:40:53.910 So you're going to get your graph here, a nice graph. 00:40:53.910 --> 00:40:55.610 And what you're going to do is you're 00:40:55.610 --> 00:40:58.250 going to interpolate now your river 00:40:58.250 --> 00:41:01.760 absorbances against the curve so you can read off 00:41:01.760 --> 00:41:03.050 the concentrations. 00:41:12.820 --> 00:41:19.330 So the concentrations in that graph are in micromolar. 00:41:19.330 --> 00:41:21.760 So you're going to want to take those and convert 00:41:21.760 --> 00:41:24.440 them to milligrams per liter. 00:41:24.440 --> 00:41:26.230 So you want to convert this first 00:41:26.230 --> 00:41:31.780 to a molarity, moles per liter. 00:41:34.930 --> 00:41:44.740 Then you take that, and you want to go down to grams per liter, 00:41:44.740 --> 00:41:47.440 and then finally milligrams per liter. 00:41:52.110 --> 00:41:54.550 So you're going to be calculating two things. 00:41:54.550 --> 00:42:02.110 You want to calculate the phosphate concentration in ppm, 00:42:02.110 --> 00:42:04.510 which is milligrams per liter, and the phosphorus 00:42:04.510 --> 00:42:06.050 concentration. 00:42:06.050 --> 00:42:10.630 So you'll take your mass from the curve in milligrams 00:42:10.630 --> 00:42:16.090 per liter, and take it times the ratio for phosphate of PO4 00:42:16.090 --> 00:42:18.040 over KH2PO4. 00:42:18.040 --> 00:42:20.770 And that ratio is 0.70. 00:42:20.770 --> 00:42:23.680 And then for phosphorus, do the same thing. 00:42:23.680 --> 00:42:26.410 The ratio there is 0.23. 00:42:26.410 --> 00:42:29.380 And this is the most important part of this lab-- 00:42:29.380 --> 00:42:32.290 this is the whole thing, calculating 00:42:32.290 --> 00:42:35.140 these concentrations in the end. 00:42:35.140 --> 00:42:39.650 So it's important to know how to do that. 00:42:39.650 --> 00:42:42.070 So once you get your concentrations, 00:42:42.070 --> 00:42:45.550 you've got a series of things to go through here 00:42:45.550 --> 00:42:48.190 for your data analysis. 00:42:48.190 --> 00:42:52.210 There's no error propagation on this part of the lab, which 00:42:52.210 --> 00:42:54.680 is good for you. 00:42:54.680 --> 00:42:57.370 You will have to use the LINEST equation 00:42:57.370 --> 00:43:01.570 that Sarah talked about, which is pretty easy to use. 00:43:01.570 --> 00:43:04.750 And that'll help you calculate the errors of your slope 00:43:04.750 --> 00:43:07.070 intercept and y values. 00:43:07.070 --> 00:43:10.120 And then you find your average and standard deviation 00:43:10.120 --> 00:43:14.080 of the five measurements, calculate the 95% confidence 00:43:14.080 --> 00:43:15.520 interval. 00:43:15.520 --> 00:43:18.460 Most importantly, report the final concentration 00:43:18.460 --> 00:43:20.980 of P and PO4. 00:43:20.980 --> 00:43:26.260 Make sure all these results show up in your abstract. 00:43:26.260 --> 00:43:28.570 First thing I do when I get lab reports is I 00:43:28.570 --> 00:43:29.920 look at the abstract. 00:43:29.920 --> 00:43:35.890 I want to see a line that shows my results. 00:43:35.890 --> 00:43:39.670 And they also should appear in your conclusion, 00:43:39.670 --> 00:43:43.970 and then you can discuss them in your discussion of your lab 00:43:43.970 --> 00:43:44.470 report. 00:43:47.700 --> 00:43:51.390 So any questions about this? 00:43:51.390 --> 00:43:55.320 I know you're going to have a busy weekend because you're 00:43:55.320 --> 00:43:58.980 going to be working on your ferrocene lab, your first lab 00:43:58.980 --> 00:44:00.360 report. 00:44:00.360 --> 00:44:02.340 And I want to tell you that please, 00:44:02.340 --> 00:44:05.370 feel free to reach out to me or Sarah 00:44:05.370 --> 00:44:07.680 if you have any questions. 00:44:07.680 --> 00:44:09.930 I'm going to be here tomorrow. 00:44:09.930 --> 00:44:13.620 I probably will be here Saturday and Sunday. 00:44:13.620 --> 00:44:16.290 So if there's a last minute question, 00:44:16.290 --> 00:44:20.910 just send me an email, and I'm happy to invite you in, 00:44:20.910 --> 00:44:24.240 and we can answer your question. 00:44:24.240 --> 00:44:26.400 I should be here in the afternoon, probably, 00:44:26.400 --> 00:44:29.190 on Saturday and Sunday. 00:44:29.190 --> 00:44:39.510 Now, I'd like to end the lecture today by doing a demonstration. 00:44:39.510 --> 00:44:41.080 Actually, did I turn that off? 00:44:41.080 --> 00:44:42.930 I can show you this here. 00:44:42.930 --> 00:44:47.100 I'm going to do this Briggs-Rauscher reaction. 00:44:47.100 --> 00:44:54.300 Actually, we're going to make this iodomalonic acid. 00:44:54.300 --> 00:44:57.480 We're going to actually attach an iodine to malonic acid. 00:44:57.480 --> 00:45:00.120 We're going to create this in a beaker. 00:45:00.120 --> 00:45:01.980 The reason I'm showing you this reaction 00:45:01.980 --> 00:45:06.720 is because it has everything in it, including starch. 00:45:06.720 --> 00:45:09.000 And it has a lot of colors. 00:45:09.000 --> 00:45:12.000 And these colors are things that we're 00:45:12.000 --> 00:45:16.140 going to talk about in the next lecture, what starch does 00:45:16.140 --> 00:45:17.290 and how it works. 00:45:17.290 --> 00:45:21.540 And this is kind of a preview to that. 00:45:21.540 --> 00:45:23.160 This reaction that you're going to see 00:45:23.160 --> 00:45:28.410 was actually discovered by two high school chemistry teachers. 00:45:28.410 --> 00:45:31.860 They're Briggs and Rauscher from Galileo High School, 00:45:31.860 --> 00:45:34.680 my favorite city, San Francisco. 00:45:34.680 --> 00:45:39.370 So these guys came up with this back in, I think, 1973. 00:45:39.370 --> 00:45:43.290 They published a paper in the Journal of Chemical Education. 00:45:43.290 --> 00:45:48.690 And they had every scientist in the country puzzled. 00:45:48.690 --> 00:45:50.940 And it took about 10 years to work out 00:45:50.940 --> 00:45:53.130 all the and sundry reactions that 00:45:53.130 --> 00:45:56.140 are going on in this reaction. 00:45:56.140 --> 00:46:00.300 So I'm going to put on some safety glasses. 00:46:00.300 --> 00:46:07.400 And what I'm going to be doing is 00:46:07.400 --> 00:46:12.270 going to be mixing three colorless solutions in here. 00:46:12.270 --> 00:46:14.280 This is my first one. 00:46:14.280 --> 00:46:17.580 And I'm going to use kitchen chemistry, which 00:46:17.580 --> 00:46:20.668 means I'm kind of looking at that scale over there 00:46:20.668 --> 00:46:21.960 and I'm going to pour these in. 00:46:32.080 --> 00:46:35.820 So let's put a little more. 00:46:35.820 --> 00:46:38.050 That's colorless, right? 00:46:38.050 --> 00:46:40.485 OK, next colorless solution. 00:46:55.610 --> 00:46:58.780 That's about right. 00:46:58.780 --> 00:47:02.120 And the final colorless solution-- keep your eye on it. 00:47:10.480 --> 00:47:14.530 Oh my goodness, wow. 00:47:14.530 --> 00:47:15.940 It wasn't supposed to do that. 00:47:22.380 --> 00:47:24.690 What? 00:47:24.690 --> 00:47:25.590 Are you kidding me? 00:47:32.400 --> 00:47:33.440 What's going on here? 00:47:37.010 --> 00:47:38.450 Get your clock out. 00:47:38.450 --> 00:47:40.120 This is a clock reaction. 00:47:40.120 --> 00:47:41.630 You can keep time with this. 00:47:53.600 --> 00:47:56.770 So I'll give you a little hint. 00:47:56.770 --> 00:48:00.940 There iodide in there, I minus. 00:48:04.060 --> 00:48:06.550 And I minus is colorless. 00:48:11.560 --> 00:48:15.580 There is iodine in there, and iodine is amber. 00:48:22.030 --> 00:48:27.520 When they're both present, it's blue-black. 00:48:27.520 --> 00:48:30.610 And we're going to see why that is in the next lecture. 00:48:36.650 --> 00:48:40.180 So there's a lot of reactions going on in there. 00:48:40.180 --> 00:48:45.640 When these reactants react, they form hypoiodous acid. 00:48:45.640 --> 00:48:50.890 And sometimes, the hypoiodous acid actually 00:48:50.890 --> 00:48:54.170 oxidizes iodide to iodine. 00:48:54.170 --> 00:48:56.720 So you've got collarless going to amber. 00:48:56.720 --> 00:49:00.650 But sometimes, there's so much hypoiodous acid formed, 00:49:00.650 --> 00:49:02.520 you can't handle everything. 00:49:02.520 --> 00:49:05.690 And what happens is you have a little bit of I 00:49:05.690 --> 00:49:08.300 minus and I2 present at the same time. 00:49:08.300 --> 00:49:09.957 And you get blue-black. 00:49:09.957 --> 00:49:11.540 This is kind of the color you're going 00:49:11.540 --> 00:49:13.250 to get when you do your titrations 00:49:13.250 --> 00:49:15.710 and you add the starch, because there 00:49:15.710 --> 00:49:19.670 is starch present in this. 00:49:19.670 --> 00:49:21.950 So I'm going to leave you with that. 00:49:21.950 --> 00:49:26.000 And I'll see some of you up in the lab. 00:49:26.000 --> 00:49:27.170 Yes, you have a question. 00:49:27.170 --> 00:49:29.120 AUDIENCE: [INAUDIBLE] 00:49:29.120 --> 00:49:32.630 JOHN DOLHUN: She just asked me if this will ever stop. 00:49:32.630 --> 00:49:35.470 Can someone-- Hannah wants to know 00:49:35.470 --> 00:49:37.520 if this is going to ever stop. 00:49:37.520 --> 00:49:43.050 Who can tell me, anyone? 00:49:43.050 --> 00:49:43.550 Aisha? 00:49:43.550 --> 00:49:46.175 AUDIENCE: I feel like it won't, because it's not releasing gas. 00:49:48.393 --> 00:49:50.810 JOHN DOLHUN: Aisha says it probably won't because it's not 00:49:50.810 --> 00:49:52.700 releasing gas. 00:49:52.700 --> 00:49:54.320 But in a minute, it's going to. 00:49:54.320 --> 00:49:57.080 Iodine vapor is going to start pouring out of it, 00:49:57.080 --> 00:50:00.470 and Tristan is going to carry it up to the lab in a bucket 00:50:00.470 --> 00:50:02.780 quickly. 00:50:02.780 --> 00:50:10.700 But in answer to Hannah's question is, will this stop? 00:50:10.700 --> 00:50:12.020 AUDIENCE: [INAUDIBLE] 00:50:12.020 --> 00:50:14.180 JOHN DOLHUN: Limiting reagent, right? 00:50:14.180 --> 00:50:17.220 There's always a limiting reagent. 00:50:17.220 --> 00:50:19.690 OK, see you.