Everything Everywhere Daily: History, Science, Geography & More - Oxygen

Starting point is 00:00:00 All around you, in the air and the ground, is the most common element on Earth, oxygen. As you are certainly well aware, oxygen is required for life on Earth as we know it, but you might not realize that the Earth didn't always have oxygen in its atmosphere. Oxygen has been responsible for everything from the rise of multicellular life to the space program. Learn more about the element of oxygen, what it is, and how it came to be in our atmosphere on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed.

Starting point is 00:00:51 It effectively turned day into night. And how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR. Before I get too deep into the discussion of oxygen, I should probably explain what oxygen is and what makes it so special. Oxygen is the eighth element on the periodic table. It also has the distinction of being the third most abundant element in the universe after hydrogen and helium, and the most abundant element in and on the earth itself. Oxygen is almost twice as abundant as silicon in the earth's makeup. What makes oxygen so special, and what you're going to need to understand to make sense of the

Starting point is 00:01:34 rest of the discussion on oxygen is that it's very reactive. Oxygen's outer electron shell has six electrons out of a possible eight. atoms really want to have full electron shells, and they can do this by bonding with other atoms and using their electrons to fill up that outer shell. Oxygen is actually one of the most reactive elements on the periodic table. When oxygen reacts with something, it's called oxidation. And, okay, just to be technical, oxidation has a more general meaning as well. If an atom gives up electrons, it's being oxidized, and if it gains electrons, it's called

Starting point is 00:02:10 being reduced. In a strict chemical sense, you don't need oxygen in an oxidizing reaction, but the name comes from reactions using oxygen because it was the first known oxidizing reagent. And this episode is about oxygen. You're probably familiar with many forms of oxidation. Rust is a form of oxidation. Burning and combustion are forms of oxidation. If you've ever seen an apple or a piece of fruit turned brown, that's because it's reacting with oxygen. So oxygen, in addition to being responsible for life as we know it, it's also responsible for decay and destruction.

Starting point is 00:02:45 Oxygen in the atmosphere is almost never in its atomic form. Instead, it tends to bind to itself to form oxygen molecules. This is usually in the form of O2, which is just two oxygen atoms bound together, or sometimes O3, which consists of three oxygen atoms and is called ozone. If we go back far enough, there was a lot of, time when the Earth's atmosphere had almost no oxygen in it. The atmosphere mainly consisted of gases such as methane, ammonia, and water vapor. The microbial life forms on this planet at that time were all anaerobic, meaning that they didn't use oxygen. Then about 2.4 billion years ago, something

Starting point is 00:03:23 happened. A form of life developed known as cyanobacteria, also known as blue-green algae, which could conduct photosynthesis. These cyanobacteria consumed carbon dioxide and gave off oxygen as a byproduct. This began what is known as the Great Oxidation Event. The addition of oxygen to the atmosphere didn't really do much at first. Given how reactive oxygen is, it would bind itself to rocks and other organic matter, quickly removing it from the air. However, over time, as cyanobacteria spread and the rocks around the world became fully oxidized, oxygen began to accumulate. And this was not good news for the microbes which were adapted to a reducing atmosphere with methane and ammonia.

Starting point is 00:04:05 This is why the Great Oxidation event has also been called the Great Oxygen Catastrophe and the Oxygen Holocaust. It resulted in the death of most life forms that existed on the planet at that time. Over the course of several hundred million years, more and more oxygen accumulated in the atmosphere, which resulted in more life forms that were adapted to oxygen. Aerobic metabolism, which uses oxygen, is more efficient at the production of adenosine trifosate,

Starting point is 00:04:32 or ATP, which is the primary molecule used for energy and cells. The great oxidation event may have also resulted in the creation of eukaryotes, which are the cells that have a nucleus and are the basis of multicellular life. Oxygen in the atmosphere kept increasing over a period of hundreds of millions of years. Today, the percentage of oxygen in the atmosphere is approximately 21%. However, there was a time when oxygen levels reached 35% at the end of the Carboniferous period, which was about 300 million years ago.

Starting point is 00:05:04 A world with an atmosphere of 35% oxygen would be a very different one than the world we live in today. For starters, you could probably breathe in that environment for at least a little while. However, over an extended period, you'd probably suffer from oxygen toxicity, a condition normally only encountered by deep sea divers. This oxygen-rich world allowed for the development of enormous insects.

Starting point is 00:05:27 Insects don't have lungs for gas exchange. They have to rely on the direct exchange of gas through their bodies. When oxygen levels increased, it allowed for more oxygen to be consumed by insects, which resulted in larger body types. The largest insect that ever existed lived in such a high oxygen environment. It was a dragonfly-looking insect with a wingspan of 27 inches or 68.5 centimeters. A 35% oxygen atmosphere would also have seen an enormous amount of fires. Combustion takes place much more easily in an oxygen.

Starting point is 00:05:59 rich environment. These fires may have resulted in the rich layer of carbon in the ground, from which the Carboniferous Period gets its name. Oxygen continues to exist in the Earth's atmosphere because of plant life, which is continually creating it. If all of the living things in the world were to disappear instantly, the amount of oxygen in the atmosphere would actually start to decrease over time. Organic matter would decay, pulling oxygen out of the air, and geologic processes would remove oxygen as well. Estimated amount of oxygen in the atmosphere would be down to just 5% within 1.5 million years and down to half a percent within 2 million years.

Starting point is 00:06:38 This is why astronomers look for signatures of oxygen as a potential biomarker for life and other planets. Any planet with an oxygen-rich atmosphere would have to have some means of replenishing the oxygen, as over time all of it would eventually react with rocks and other chemicals. While oxygen has had a pivotal role in the creation of life on Earth, humans actually had no clue that it even existed for thousands of years. There were philosophers who believed that there was something in the air which was responsible for life. The 17th century Polish scientist Michael Sen de Vogueus called it Kibus Vite, or the food of life, and went so far as to identify it as the gas that was given off when potassium nitrate was heated. That gas was oxygen. Over a century

Starting point is 00:07:23 later, in 1772, the Swedish chemist Karl Wilhelm Schill created a substance called fire air by heating various substances such as mercury oxide. It was the only substance he could find that would support combustion rather than extinguish it. In 1774, the English scientist Joseph Priestley discovered what he called deflogisticated air. However, it was the French chemist Antoine Lavassier who figured out that the substance that Priestley and Shield discovered was in fact a new element. He dubbed the new element, oxygen, which came from the Greek words oxus, which means acid, and gens, which means the creation of. Levoisier mistakenly thought that oxygen was a part of every acid. In 1877, the French chemist Raoul Pierre Picquette liquefied oxygen for the very first time,

Starting point is 00:08:09 even though he only managed to create a few drops. Oxygen doesn't become a liquid until it reaches a temperature of minus 182 degrees Celsius or minus 297 degrees Fahrenheit. In 1891, the Scottish chemist James Dewar managed to create enough liquid oxygen to actually study. It turned out that liquid oxygen exhibited properties that weren't expected, given how gaseous oxygen behaves. For starters, liquid oxygen isn't colorless. It actually has a light blue color. You can see videos online of experiments using liquid oxygen where you can clearly see its bluish hue.

Starting point is 00:08:46 The other amazing property of liquid oxygen, and this is one that nobody expected, is that it's paramagnetic. It doesn't act as a magnet per se, but external magnets can, influence it. Liquid oxygen turned out to be extremely useful. For starters, you can have a lot more oxygen in liquid form than you can in gaseous form. Oxygen has an expansion ratio of 861 to 1, meaning that liquid oxygen will have 861 times more oxygen than gas at standard temperature and pressures in the same volume. There are many applications where you want to have pure oxygen. One of the biggest is in rockets and spaceflight. Rockets require combustion, and combustion requires oxygen. However, the higher-upper rocket goes, the less oxygen there is,

Starting point is 00:09:32 and when you're in space, there's no oxygen at all. The solution is liquid oxygen. Liquid oxygen, plus some sort of fuel such as liquid hydrogen, kerosene, or methane, can provide combustion and thrust even in a total vacuum. Pretty much every liquid-fueled rocket, including the Saturn 5 used in the Apollo program and the space shuttle, have used liquid oxygen. Liquid oxygen can also be used for industrial purposes, mostly just as a convenient storage and transportation vehicle for pure oxygen. Pure oxygen can aid in combustion when something needs to burn hotter or more efficiently than just using the oxygen and air. The biggest single commercial use for oxygen is in the production of iron and steel. A jet of pure oxygen is injected into molten iron, which then removes impurities.

Starting point is 00:10:19 Another big user of liquid oxygen is in the chemical industry, where pure oxygen is used to make various chemical compounds that include oxygen. Another big use of pure oxygen is in cutting and welding applications. A stream of pure oxygen can create a hotter flame, making it possible to cut and weld metals. The application that most people are probably familiar with is the medical use of oxygen. Supplemental oxygen is often given to people who have pulmonary or circulatory diseases where not enough oxygen is able to get into the body. By breathing oxygen with a higher partial pressure than the atmosphere, more oxygen is able to get into the blood. High-pressure oxygen treatments are used on people who've suffered from decompression sickness or

Starting point is 00:11:01 carbon monoxide poisoning. By putting them in an environment with more oxygen, it's possible to displace the carbon monoxide that's been bound to the oxygen receptors in hemoglobin, the molecule that transports oxygen in the blood. In the case of decompression sickness, high-pressure oxygen can help redissolve nitrogen bubbles in the body, which occurs usually when scuba divers ascend too rapidly. Supplemental auction is often used by mountain climbers who climb peaks like Mount Everest where there is very little oxygen at the top. Likewise, pilots in military aircraft will often use supplemental oxygen when flying at extremely high altitudes. In commercial aircraft, during an emergency, oxygen mass will often drop to allow people to breathe during a loss of pressure

Starting point is 00:11:43 at high altitudes. The oxygen in these systems usually doesn't come from oxygen canisters, but rather is produced on demand via a chemical oxygen generator. These will usually consist of iron filings which are mixed with sodium chlorate to produce oxygen. By using a chemical oxygen production system, it isn't necessary to have high-pressure tanks on board a plane, and you don't have to worry about the tanks leaking. One place you've probably seen oxygen being used is on the sidelines of sporting events. Believe it or not, there's actually very little evidence to indicate that this does anything beyond a placebo. effect, as there is a limit to the amount of oxygen that hemoglobin in your blood can support.

Starting point is 00:12:24 Breathing oxygen can produce a euphoric feeling, which is probably the reason why people think it works. And it's also the reason why you sometimes see oxygen bars. I've seen these in several airports around the world. You literally sit down to breathe oxygen out of a tube for several minutes. It can produce a temporary euphoric feeling, but it really doesn't do anything beyond that. Oxygen is everywhere, and most of the major life forms in the world depend on it in one way or another. We use it for industrial purposes and in medicine, and one day its presence might even let us know that there's life somewhere else in the universe. And that's not too bad for a gas that didn't even exist in our atmosphere 2.5 billion years ago. The executive producer of Everything Everywhere Daily is Charles Daniel.

Starting point is 00:13:12 The associate producers are Thor Thompson and Peter Bennett. Today's view comes from listener Bazawe over on Apple Podcasts in the United States. They write, Gary is my fishing buddy. I recently become a completionist club member after listening to over 1,000 episodes, mostly while fishing. Thank you for being such a good companion. Gary's voice is perfect at one and a quarter speed,

Starting point is 00:13:33 and the topics are interesting and informative. Thank you from another proud Wisconsinite and Packer fan. My all-time favorite is the Pesh to Go Fire episode. I thought I knew all about it, but I learned a lot. keep up the great work. Well, thanks, Bazawi. I'm happy to welcome you to the Wisconsin chapter of the Completionist Club. The Wisconsin Chapter is actually a supper club that serves brandy old fashions,

Starting point is 00:13:55 and of course, fish every Friday. You can have your choice between perch or walleye. Remember, if you leave a review or some of the boostogram, you two can have it read on the show.

Everything Everywhere Daily: History, Science, Geography & More - Oxygen

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