Laws of Thermodynamics

So now that we know that thermodynamics is the study of energy and energy transfers in this video, we're going to introduce the first law of thermodynamics. And so the first law of thermodynamics basically says that energy can be transferred from one substance to another. Substance and energy can also be transformed from one form into another form. But energy cannot be created or destroyed. And so this is why the first law of thermodynamics is also known as the principle of conservation of energy. And this is again because the total amount of energy in the universe is conserved, meaning that it does not change. And so the total amount of energy before ah process is going to be equal to the total amount of energy after a process. Since energy is not created or destroyed again, energy can be transferred from one substance to another, and it can be transformed from one version of energy into a different version of energy, such as, uh, kinetic energy into potential energy and vice versa. But again, energy cannot be created or destroyed, and this is basically with the first law of thermodynamics, says so let's take a look at our image down below to get a better feel for this first law of thermodynamics. So notice that in this image over here we're showing you a plant cell over here on the far left. On zooming in here, you can see that we have our plant. And inside of the plant we have this chloroplast which recall performs photosynthesis. And then over here on the right hand side, we're showing you a new animal cell right here on. We're zooming into this little bunny rabbit, which is an animal, and you can see that the bunny here We're zooming into this mitochondria here which performs cellular respiration and so also noticed that we have the sun here. And the sun is really where most of the energy of life is going to originate from. And so the sun's energy, it's solar energy can be captured by photosynthetic organisms such as plants that perform photosynthesis and photosynthesis is capable of transfer, transforming the solar energy into chemical energy of glucose. It also creates some oxygen in the process. But what you can see is that energy is being transferred from the sun and being transferred from the sun to create a different type of energy, chemical energy here. And so what we're saying is that energy is transferred, but once again, it cannot be created or destroyed. Now, uh, the animal cell over here, the little bunny rabbit is able to eat the leaves and eat the plant. And when it does that, it can obtain the energy of the glucose. And then it can use the energy of the glucose to create a different type of energy a teepee energy that can be used by the cell. And so ultimately, what we're seeing is that, uh, energy can originate from the sun. It can be converted into chemical energy of glucose. It could be transferred to other organisms, such as little bunny rabbits that can eat them. And then, of course, the bunny rabbits. When the bunny rabbits pass away, and also, when they conduct cellular respiration, um, they can transfer their nutrients over back to plants, and so they're able to create carbon dioxide and water that photosynthesis is able to take advantage of. And so here. What we're saying is that the first law of thermodynamics is that energy can be transferred and transformed into different versions but once again it cannot be created or destroyed. And so you can see the energy here is flowing in this direction, and it just cycles between different forms, but it's never created or destroyed. And so this year concludes our brief introduction to the first law of thermodynamics, and we'll be able to get a little bit of practice as we move forward in our course, So I'll see you all in our next video.

Now, before we get into the second law of thermodynamics, it's first important to understand the idea behind this term called entropy. And so entropy is defined as a measure of disorder or, in other words, a measure of randomness. And so the greater the disorder is, the higher the entropy will be. And so let's take a look at this image down below right here to get a better understanding of entropy. And so notice over here on the left hand side, we have this pool table, and the billiard balls here that you see are very, very highly organized and very, very ordered. However, notice over here on the right hand side, this pool table has the same billiard balls here that are scattered throughout the entire table, and so they're not very highly ordered. They're not very highly organized and said they're pretty greatly disordered over here. And so because they are mawr disordered over here, the greater the disorder, the higher the entropy. And so this system over here is going to have higher entropy. And, of course, this system over here that is highly ordered and not very disordered. It's going to have low entropy and so the lower the entropy the Mawr organized in the mawr ordered it ISS, whereas the higher the entropy, the mawr disordered it is and the more unorganized it iss. Now, the natural tendency of reactions is to move the universe towards a state of maximum entropy, or maximum disorder. And so the natural tendency of the universe is for things to go from ah state of order, uh, towards a state of disorder, a state of higher entropy. This represents the natural tendency of reactions. However, reactions can decrease entropy of a system essentially going backwards in this direction with an energy input and so you can see down below that with an energy input, reactions can become mawr ordered. And so this is really what life is capable of doing. Living organisms are capable of in putting energy so that they can create order, um, in their systems. But the natural tendency of the universe is to go from a state of low entropy towards a state of higher entropy. And so the reactions are gonna have this tendency to move towards the state of maximum entropy, or maximum disorder. And so this is an idea that you would get to learn a lot more about in a chemistry course. But here in our biology course, this concludes our introduction to entropy, and we'll be able to apply entropy in the second law of thermodynamics, which will cover in our next video, so I'll see you all there.

in this video, we're going to introduce the second law of thermodynamics. And so the second law of thermodynamics can actually be stated in many different ways. And so it's possible that your professor or your textbook might state the second law of thermodynamics in a different way. But really, all the second law of thermodynamics is trying to say is that 100% efficient energy conversion is impossible, since heat energy is going to be lost with every energy transfer. And this is going to lead to the increase of the overall universal entropy. And so heat is going to be defined as a form of kinetic energy that is going to be transferred between two objects with different temperatures. And so let's take a look at our example down below at the second law of thermodynamics to get a better understanding of the second law of thermodynamics and so notice that we're showing you a similar process to our last lesson video on the first law of thermodynamics. And so you can see that, uh, the sun is really going to be the, uh, the energy provider where most of the energy is going to originate from from life. And so you can see that the energy transfer here from solar energy uh, two plants is going to be accompanied by a loss of heat. And so, with every energy transfer, uh, there's going to be some of the energy that is lost is heat, and so there's not 100% efficient energy conversion. Some of the energy is lost as heat, and that heat is not going to be a usable form of energy by the organism. And the same goes between when an organism might eat. Uh, you know the leaf. The energy transfer here is gonna be accompanied by a loss of heat. And the same goes when the fox here eats the lead. Uh, the mouse there's gonna be a transfer of energy, but some of the energy is going to be lost in the form of heat. And this heat that is being lost with every energy transfer is going to lead to the increase in the entropy of the universe. And so the entropy of the universe is always going to be increasing with every energy transfer. And so this here is really what the second law of thermodynamics is referring to the increasing of universal entropy with every energy transfer. And so this here concludes our introduction to the second law of thermodynamics, and we'll be able to apply some of the concepts that we've learned here as we move forward in our course, So I'll see you all in our next video.