As we discussed in the previous video, we talked about how in chemistry you really need to understand matter and energy. And we spent most of our time talking about matter and how it's the physical material that we are made of and that we interact with on a daily basis. We also conclude the video talking about how matter stores energy and in fact, if you paid attention to that equation E=mc squared that Einstein came up with. You might realize that matter can store a lot of energy that is a small bit of matter can store a tremendous amount of energy. So what is energy? Well energy has many definitions, but for simplicity we will just define it as the ability to do work that is move objects or transfer heat. Energy is persistent, it can not be created nor destroyed, only transferred or transformed. What do we do with energy? Well we use it for almost everything, we use it to power light bulbs, to light our homes at night, we use it for cell phones so we can communicate with each other. We use it to drive to work or school, we even use it to travel to outer space. We use it to do homework, we use it to do our laundry, we use it to build new buildings. All right, and the list goes on and on and on. And one of the best things that we do here at UNC is we use energy to watch the Tar Heels beat up on Duke. So where do you think we get all this energy from to do all these things that we do? Maybe you think it comes from fossil fuels like oil and coal, or food or nuclear power plants, or solar and wind power plants, right? And it's true, these are all sources of energy, but all of that energy actually comes from the sun, how does that work? Well, as I mentioned before, energy is transferred from one thing to another, it's never created, never destroyed. So the sun, which shines all across the planet, may feed organisms called Phytoplankton. These are tiny microorganisms that can use a process called photosynthesis to convert the sun's energy in the form of light, into sugar molecules. These phytoplankton are then consumed by zooplankton thereby transferring their energy that they converted from the sun into energy that the zooplankton can use to swim around, right? Zooplankton include little animals like krill a major food source for fish. All right, and fish is a major food source for humans. Now where is the fossil fuels paleontology, where do those come from? Well, millions of years ago, phytoplankton as they were very numerous in population in ocean. They died, and they drift out to the bottom and there be tons and tons and tons of phytoplankton just littering the ocean floor. They get buried, and then after millions of years of high heat and pressure their little tiny cell bodies were converted into crude oil. And, of course, we use crude oil to do all kinds of things. So we're actually extracting the energy from the phytoplankton in a couple of ways. On land, this process works very similarly, the sun shines on plants like the trees in forest. And over millions of years, forests had been buried and covered by a lot of earth and they produced another fossil fuel that we use, coal Which we use for power plants as well and not only do we use the sun's energy to provide fossil fuels right. We didn't just get the sun's energy that way but we also get it through our foods that we eat. For example the sun feeds corn and other types of crops and these crops are then in turn used to feed livestock like chicken, pigs, cattle. And we consume those animals as well. So the suns energy can be transferred to us via plants, directly or through other animals. What does all of this really mean? Well it means that all of the matter on Earth, all the living organisms that are on the Earth are actually just storage vessels for the suns energy. We're all batteries. [MUSIC] So why study chemistry? Well, a major goal of science is to understand and explain natural phenomena and, in many cases, take advantage of that knowledge to advance humanity's technological capabilities. Chemistry in new medicines that have saved countless lives we create new materials like the plastics that make your cell phones harder to break. We make sure that we have clean drinking water and are always looking for better ways to meet our energy demands in a sustainable way, just to name a few of the things that chemists do. Speaking of sustainable energy, one of our biggest problems today actually come from our energy source, our major energy source, fossil fuels. By the rate at which we globally use fossil fuels for transportation, electricity, agriculture and so on, we release over 35 billion tons of carbon dioxide into the atmosphere every year. This is the most ever in recorded history. The consequences of this are already being felt by communities all across the planet experiencing droughts. Having 10 of the record hottest years ever to happen in the last 15 years, rising sea levels, mass extinction events, and the list goes on. How does a chemist use critical thinking to solve a problem like this? One possible solution is to think about how energy and matter are related and that would lead us to possibly come up with better fuels. So if we think about one fuel that you're probably very familiar with, gasoline, the major molecule in gasoline is called octane. Octane is a molecule that has 8 carbon atoms and 18 hydrogen atoms bound together to form a really long carbon chain that we can burn and produce heat energy to power a car. In this reaction, you have 2 molecules of octane. It reacts with 25 molecules of oxygen to produce 16 molecules of carbon dioxide and 18 molecules of water. Another key to this, if you pay attention to this chemical equation, is that only 2 molecules of octane produce 16 molecules of carbon dioxide. That's 8 times as much carbon dioxide as the number of molecules of octane, that's a lot of CO2. So if we consume millions of tons of octane, it ends up becoming billions of tons of CO2 which is very bad for the environment. Now why do we even use octane and fossil fuels in the first place? Well, they're really easy to get our hands on. They're just below the surface of the Earth's crust, you can drill down and access them, and you get a lot of energy out of these fuels. These fuels originally, as I mentioned before, come from these phytoplankton that converted the sun's energy into some other form of energy. In this case, we're talking about molecular or chemical energy. The problem with these fuel sources is that they're not very efficient at releasing heat energy. Part of that is that plants and other living organisms just aren't that efficient at converting solar energy into useful energy. The critical thinking chemist is going to say, well maybe we can come up with a better fuel, a simpler fuel, that will not produce CO2. What kind of fuel could that be? Well, let's look hydrogen gas, H2. If we combust that with oxygen, the only thing it produces is water, no CO2. And as we get better at being able to produce hydrogen, which is one thing that we're really working very hard on, we'll be able to come up with a sustainable energy source that will also not cause pollution. Being able to think like a chemist is not only useful in helping you better understand what's happening in the world around you. But it can provide a set of tools to help you solve some of the world's biggest problems.
