Ever wonder what makes your coffee cool down or how your car engine harnesses energy? It's all thanks to thermodynamics. It's a pretty mind blowing field. It really is. And today, we're diving deep into it. Think of it as your cheat sheet for understanding the energy that powers our universe. Exactly. We'll be using excerpts from thermodynamics, Dorn showed. It's a chemistry course website we're using as our guide. But don't worry. We'll make it fun and insightful. Promise. Absolutely. So let's start with the basics. Okay. How does thermodynamics Dornshow define this field? Well, it's essentially the study of how heat, work, temperature, and energy all relate to matter and radiation. So it's like the rule book for how energy behaves. It's about understanding how energy interacts with the physical world. Yeah. But the rule book for the entire universe seems a little ambitious, doesn't it? It is a big concept. How can we possibly define a system that big? That's why we break it down. Okay. We define specific systems and their surroundings. Okay. Imagine your coffee cup. That's our system. Okay. Everything else, the room, the air, even us becomes the surroundings. Okay. And together, they represent a mini universe. That makes so much more sense. Right. So when we talk about energy being constant, we're talking about the total energy within a defined system like that. You got it. Mhmm. This is where the first law of thermodynamics comes Mhmm. In the idea that energy cannot be created or destroyed, only transformed. Think of it like a giant cosmic bank account. Okay. You could deposit energy in different forms, heat, work, even something like light. Right. And you can withdraw in different forms, but the total amount always remains the same. Mhmm. Wow. That's mind blowing. So every time energy changes forms, it's like the universe is keeping a meticulous balance sheet. Exactly. Now let's break down those forms of energy a bit further. Think about the energy of motion like a speeding baseball. Okay. That's kinetic energy. And the faster that baseball's going, the more kinetic energy it has. Right? Precisely. Thermodynamics Dorn showed, I think, gives a specific example. A baseball moving at a decent speed packs about a 102.4 joules of energy. Okay. That's a unit of measurement for energy. Okay. So that's kinetic energy on the move. Right. What about the other kind of potential energy? Think of that same baseball held high up just before you throw it. Okay. That's potential energy energy of position. It's not moving yet, but it has the potential to be set in motion. Or imagine a stretched rubber band full of pent up energy ready to be released. Oh, or what about the chemical energy stored in gasoline? Yes. That's a form of potential energy. Right? Absolutely. It's not actively powering your car just sitting in the tank, but it has the potential to release a lot of energy when it undergoes combustion. Right. And thermodynamics, Dorn showed, provides a table listing even more forms of energy. Thermal, electrical, nuclear, It's a pretty comprehensive list. It's incredible to think about how much energy is stored in different forms all around us. It really is. And speaking of energy, we've got to talk about heat, that feeling of warmth we all know so well. Absolutely. And thermodynamics Dorn showed reminds us that heat is really just the transfer of thermal energy, always flowing from hotter objects to colder ones. Right. It's like nature's way of trying to even things out. So, like, how my coffee always seems to cool down to room temperature no matter what? Exactly. That's the second law of thermodynamics in action. Right. It states that over time, differences in temperature within a system tend to even out, reaching a state of equilibrium. And I'm guessing that's related to entropy? It is. I remember learning about that in school, something about disorder. You're right. They are connected. Yeah. Entropy is this fascinating concept that describes the tendency of systems to move toward a state of greater disorder or randomness. Okay. It's like how a messy room, you know, seems to get messier over time unless you put in the energy to tidy it up. Okay. That makes sense. So more arrangements, more randomness equals higher entropy. Exactly. Now imagine combining 2 bottles of water into a larger container. Thermodynamics Dorn Schood uses this example to illustrate how the water molecules now have more space to move around more possible arrangements and therefore higher entropy. So if something causes a change in entropy in either the system or are the surroundings, it affects the entire universe's entropy. It does. And that's the key to understanding if a process will happen spontaneously. Okay. If a process increases the universe's entropy, it's favorable. It's gonna happen naturally. Okay. But if it decreases the universe's entropy, it's gonna need some help from an external source of energy. So it's all about increasing that universal entropy, basically. In a way, yes. Okay. And thermodynamics, Dorn Schmidt, actually walks us through a calculation example showing how transferring heat between objects at different temperatures impacts entropy, which then determines if the process will happen spontaneously. It's amazing how a few numbers can reveal so much about how the universe operates. It really is. Now what about heat capacity? Is that why some things heat up or cool down faster than others? That's exactly what it describes. Think about it. It takes more energy to boil a pot of water than it does to simply warm it up a few degrees. That makes sense. So different substances have different heat capacities. Yes. And different states of matter like solids, liquids, and gases also have an impact. You're getting it. Thermodynamics Dornshood points out how heat capacity varies between those states of matter, and they provide some helpful practice problems for us to solidify these concepts. Practice problems are always welcome. It's like flexing those mental muscles. So we've talked about heat, entropy, and heat capacity. We have. What's next on our thermodynamic adventure? It's time to talk about energy on the move. Okay. So how does energy get around? There are 2 main ways, heat, which we've already explored Right. And work. And to understand work, we need to talk about internal energy. Internal energy. Is that, like, the energy hidden deep inside something? In a way, it's the total energy within a system. Okay. But here's the catch. You can't easily measure all of it directly. Oh. Think of it like an ocean planet as thermodynamics Dorn showed suggests. You can't easily measure all the water, but you can measure the changes when you add or remove some. That's a brilliant analogy. So we focus on the changes in internal energy. Yes. And those changes depend on heat and work. You've got it. Okay. We could even represent this with an equation. Change in internal energy equals heat plus work. So if a system absorbs heat and has work done on it, its internal energy goes up. Exactly. It's like making a deposit into that internal energy bank account. Okay. And if the system releases heat or does work on its surroundings, its internal energy decreases. It's all about the balance between these energy exchanges. Okay. That makes sense. Now let's zoom in on work a bit more. What exactly is work in a thermodynamic context? It's a great question. And thermodynamics Dorn should focuses on a specific type of work called pressure volume work. Okay. Imagine a piston in a cylinder, like in a car engine. When you heat the gas inside, it expands, pushing the piston and doing work. Ah, that's why they use that example. So the expanding gas is doing work on the piston. Precisely. And we can even calculate that work using a specific equation. They even walk us through a practice problem calculating the change in internal energy for an expanding gas, which is incredibly helpful. I always appreciate a good practice problem. It helps solidify things. Now I'm curious about this term enthalpy. Is it related to heat and work as well? It's definitely related. Enthalpy is a way to describe heat changes at a constant pressure, which is a pretty common scenario in chemistry. Okay. So it's like a simplified way to look at at heat flow when the pressure stays the same. Exactly. And the change in enthalpy is equal to the heat exchange at constant pressure. Okay. Thermodynamics Dornshund points out that under these conditions, we can essentially think of enthalpy change as the heat absorbed or released. That does simplify things. But before we go any further, can we take a step back and clarify the difference between state and path functions? Of course. Remember that mountain climbing analogy I mentioned earlier? Yes. That's the perfect way to understand this concept. Oh, right. The one where the distance you travel depends on the path you take. Right. But the change in altitude only depends on where you start and where you finish. You got it. Okay. Distance traveled is like a path function. Okay. In thermodynamics, heat and work are path functions Mhmm. Because they depend on how a system got from one state to another. But the change in altitude, that's like a state function. It is. And in thermodynamics, that would be things like enthalpy, energy, and entropy. Yes. They only depend on the initial and final states. Exactly. It's about the destination, not the journey. Now are you ready to tackle enthalpy of reaction? Bring it on. I'm feeling pretty confident in my thermodynamics knowledge so far. That's the spirit. Now remember how we discussed standard state earlier? Yes. This is where it comes into play again. Right. So we're talking about specific standardized conditions that provide a reference point for calculations. Precisely. Thermodynamics Dorn Schood reminds us that these standardized conditions like a pressure of 1 bar help us ensure consistency in our thermodynamic calculations. And that allows us to determine the standard enthalpy of formation, the enthalpy change, when creating 1 mole of a substance from its elements in their standard states. You're on a roll. And the really cool thing is that thermodynamics Dornshund provides tables with these values for different substances. So we can just look them up. That's handy. It is. And once we have those values, we can calculate the standard enthalpy of reactant, the enthalpy change for any given reaction. They even give us a specific example in thermodynamic Dornshund, the combustion of methane. A classic exothermic reaction. Right. And they emphasize how these values are tied to the stoichiometry of the balanced chemical equation. So the enthalpy change depends on the amount of reactants involved. Exactly. Like burning 1 mole of methane versus 2 moles would produce different enthalpy changes. Exactly. Now let's put this into practice with a problem. Okay. Imagine we wanna determine the standard molar enthalpy of reaction for hydrogen gas reacting with chlorine gas to form hydrogen chloride gas. Okay. Sounds like a challenge. Where do we even begin? Just like with any good chemical calculation, we start with a balanced chemical equation. It's a road map. Alright. So the equation would be h 2 +2ields2hcl. Perfect. Now Now we need to put on our detective hats and gather the standard enthalpies of formation for each of those molecules. And we can find those values in those handy tables thermodynamics Dorn should mention. Right? You got it. And once we have those, we can plug them into our trusty equation. Okay. Enthalpy of reaction equals the sum of the products, enthalpies of formation minus the sum of the reactants' enthalpies of formation. Don't forget those stoichiometric coefficients. We need to multiply those enthalpies of formation by the numbers in front of each molecule in the balanced equation. You're on fire today. Yeah. That's exactly right. Okay. I think I'm following. Once we do all those calculations, we'll have the standard molar enthalpy of reaction for that specific reaction. This is starting to feel very practical. That's the beauty of thermodynamics. Yeah. We're not done yet. Oh. Let's shift gears slightly and consider phase changes like water boiling or freezing. So instead of a chemical reaction, we're talking about a substance changing its state of matter. Precisely. And the great thing is we can still apply the same principles of enthalpy. Okay. For example, think about the vaporization of water, liquid water turning into steam. Which we know is endothermic. It requires algae to break those hydrogen bonds between the water molecules. Exactly. And we can calculate the enthalpy change for this process known as the enthalpy of vaporization, using the same approach as before products minus reactants. And I'm guessing the enthalpy of condensation steam turning back into liquid water would just be the opposite sign. You're sharp today. Reversing a reaction simply reverses the sign of the enthalpy change. It's a handy rule to keep in mind. Okay. I've filed that away in my thermodynamics toolkit. Good. Now pop quiz. What happens to the sign of a thermodynamic state function when we multiply the reaction by a number? Well, if reversing the reaction reverses the sign, I'm gonna guess that multiplying the reaction multiplies the sign of the state function by that same number. You're on a roll. Nick. Your intuition is right on target. Yes. Now how about we move on to some experimental techniques? Okay. How do we measure these enthalpy changes in a lab setting? Sounds like a plan. I'm always a fan of seeing theory put into practice. Excellent. Then let's talk about calorimetry. Calorimetry. Sounds like a fancy word for measuring heat. It kinda is. Is it as complicated as it sounds? Not really. It's simply a technique for measuring energy changes, particularly heat flow, based on temperature changes. Mhmm. Thermodynamics, Dorn Shud, explains that we use a device called a calorimeter to track these changes. Okay. And they can be as simple as a coffee cup or as sophisticated as a bomb calorimeter. A bomb calorimeter. Yeah. That sounds kinda intense. It does, doesn't it? But don't worry. It's all carefully controlled. Yeah. Thermodynamics Dorn Schuett explains that bomb calorimeters are especially useful for studying explosive combustion reactions Okay. Because they keep a constant volume, which allows us to directly measure the change in internal energy. That makes sense. So we have different types of calorimeters for different situations. We do. What about those situations where it's difficult to directly measure the enthalpy change? Right. Is there a way to figure it out indirectly? You're in luck. Yeah. That's where Hess' law comes in. Okay. I've heard of Hess' Law. It's like a shortcut. Right? Yep. Exactly. Imagine you're hiking up a mountain. Okay. Hess' Law is like knowing the total elevation change from the base to the peak regardless of the path you take. Okay. It doesn't matter if you hike straight up or take a winding trail. The total change in altitude is the same. So with Hess' law, we can figure out the overall enthalpy change for a reaction even if it takes multiple steps. You got it. Thermodynamics Dorn Chid uses the formation of carbon dioxide as an example. Okay. It can happen in one step or 2, but the overall enthalpy change remains constant. So we're basically piecing together known information to figure out the unknown enthalpy change Right. Like solving a thermodynamic puzzle. A perfect analogy. Yeah. And thermodynamic storage should even gives us a practice problem to illustrate this concept. Okay. We use Hess's law to calculate the enthalpy of formation for acetylene. I'm starting to appreciate just how interconnected all these concepts are. They really are. And thermodynamics Dornshed does a great job of highlighting how these principles influence everything around us. Mhmm. From the way energy flows and chemical reactions to how engines work. Right. It's even woven into the fabric of the universe itself. That brings us to our final thought for our listeners today. We've talked a lot about entropy, the tendency towards disorder in the universe. Right. What does this constant increase in entropy mean for for the concept of time? That's a question that has puzzled physicists and philosophers for centuries. Right. Some say that entropy is the arrow of time, always pointing towards a future of greater disorder. Wow. That's a pretty profound concept to end on. It is. But that's the beauty of thermodynamics. Yeah. It prompts us to think about the universe in new and fascinating ways. And who knows? Maybe you'll be the one to solve the mystery of entropy and time. I wouldn't mind giving it a try. On that note, we'll leave our listeners to ponder these big questions. Keep those thermodynamic wheels turning. Yes. You never know what moments await as you continue to explore the world around you. And thank you for joining us on this deep dive. Until next time, keep asking those curious questions.