 Hello students. Good evening. Can you hear me? Yeah. So yes, good evening. So today we are going to start a new chapter that is thermodynamics. Okay. So you must have done this chapter in physics also. Yes. Yes, respond guys. Have you done this chapter in physics? Not yet. Okay. Okay. What's going on? Okay. So there is a bit difference in physics and chemistry of thermodynamics. Right. Convention wise, if you see, we have some difference. Like in physics, you have to study you know, about Carnot cycle and all. Okay. Yeah. So yeah, fine. So chemistry, thermodynamics, and please some thermodynamics, we have a bit of difference. Convention wise, like there in here in chemistry, we have worked them on the system. If I tell you the example, worked them on the system is positive. Worked them by the system is negative. It is opposite in physics. Okay. So you have to be a bit careful when you are solving this question, whether it is, you know, assignment or test. Right. So let's start with the chapter. Okay. This chapter is a bit different from all other chapters that we have done so far in chemistry. Okay. Different in that sense. Today in the session, like three and a half hour session we have, we are going to have mostly, you know, theory only because a lot of terms, new terms, you have to understand first, those terms will be using continuously, frequently in the chapter later on. Right. So first of all, we need to understand various terms, then various kind of processes we need to understand. We need to understand what are thermodynamic properties, what are thermodynamic quantities. Right. And then we will see the application of all those things later on. Right. So today you are going to have the basic understanding of this, the terms that we are going to use in the chapter, those terms we are going to understand. Right. Based on these things, like on the basic understanding of it, you will be having one assignment also today, you will get. Right. I will share one, one DPP, DPP one I'll share based on all these things you can go through. Maybe all the questions you won't be able to solve. But yes, whatever you can, you can try those that DPP ones. Okay. So let's start with the chapter. See, one thing I'm not telling you this, all these things to, you know, to make you scared or something like that. This chapter is so far the, you know, the toughest chapter we have so far, whatever chapters you have done in physical chemistry, this is among all those among all them, like this is the toughest chapter we have. It's not like you won't understand the concept or the concepts are difficult to understand. We have a lot of, you know, assumptions that we take, like under this condition, this will happen. If the condition is this, this will happen. So those kinds of things you need to understand. Okay. If you keep those conditions in mind, obviously you don't have to memorize it. You have to think on the given condition in the question, like this condition is given. So this is the probable way or the probable answer of the question or the concept we should use this particular concept since the condition is this, like this, you need to think if you know, really want to understand this chapter. Okay. So thermodynamics, this chapter, we are going to study in two parts. Okay. The first part is we are going to understand, obviously the thermodynamics we have, we'll talk about enthalpy, heat, work, no entropy, Gibbs free energy, everything we're going to understand. The first part we are going to understand, we call it as thermodynamics itself. Okay. In some book, they have given this two different chapters. Okay. Thermodynamics, we will study about various processes, thermodynamic quantities. Okay. Work done, heat, entropy, Gibbs free energy, etc. All these things we will study over here. The second part of this chapter we have that we call it as thermochemistry. Okay. Thermochemistry. Thermochemistry is very important for need point of view. Okay. If you look at need portion, in need, they ask questions from thermochemistry very frequently. Okay. It's not like they don't ask this, but the kind of the nature of this particular portion that we have, if you are able to do the question, you can do it in a minute. Otherwise, you won't get it. Right. This kind of questions. There's so many things we need to understand here in thermodynamics. Maybe if you miss one or two things, and if the question comes on that particular concept, you won't be able to solve it. Right. But thermochemistry, we don't have much concept. We have various definitions like enthalpy of formation, enthalpy of neutralization, enthalpy of combustion, those kinds of things we have. And then based on that, very basic numericals. One law we have here, which we call it as Hess's law. Have you heard this name? Hess's law. This we are going to understand. Okay. Based on this, you will get numericals, basic numericals you'll get. Correct. This is one thing very important for need point of view. If you look at the previous question, right, they definitely ask question from this need point of view. And if you've done this particular questions properly, you will get the questions from this. Here you are not very sure with. Okay. Maybe few concepts you miss and you won't be able to solve the question over here. That is the advantage of this particular portion. Okay. So this is the two portion we are going to discuss in this chapter one by one. First we'll start with thermodynamics and then we'll move on into thermochemistry. This is a smaller one. Like we can finish this in one or two hours in that way. Okay. So what is thermodynamics? First of all, and like I said, what we are going to understand over here, some thermodynamics as you are doing in physics also, this term stands for two different terms over here. Like thermal and dynamics. Dynamics, simple means motion. Okay. Dynamics means motion or flow. Right. Anything which is moving, we started, you know, rotational, it's like kinematics that we have rotational mechanics. Okay. Where we discuss about the motion of the moving objects, right, circulatory motion, many of the things we have. So dynamics is nothing but motion or flow. Thermo stands for thermal and thermal means heat. Right. So it is a motion or flow of heat. This chapter deals with, this chapter deals with, in short, I'll write down here, this chapter deals with motion or flow of heat. Okay. It also deals with the physical, feasibility of process, feasibility of reaction you can say, feasibility of reaction you can say, or the feasibility of processes, right, reaction. Under what condition the reaction is possible? Simple example I'll give you. Okay. Carbon plus oxygen gives CO2, correct. You are sitting in the room, there must be some wooden furniture, right? That is made up of carbon. And atmosphere we have oxygen. Why not the carbon, the chair on which you're sitting in, that carbon and oxygen combines and forms CO2? That reaction is possible, but it is not happening, right? Why? Because the condition is not there. So for every condition, every reaction, we have certain condition, right? That condition must be fulfilled for the reaction to, correct? So that we call it as, yes, whatever, yes, required temperature is not there, fine. Whatever the condition, but the condition must be satisfied, right? The condition must be fulfilled for any reaction to process, right? Hence, this particular thing we call it as the feasibility of reaction. Physibility means what? The reaction is possible or not under a given set of condition, correct? So all these things we are going to understand here in thermodynamics. What is the condition for feasibility of reaction? Have you heard the term gifts-free energy, delta G? Have you heard this term? Gifts-free energy, delta G, right? Delta G is the, you must have done this in a school, right? Delta G is the gifts-free energy, yeah. So the necessary condition or the feasibility of reaction, the condition is what? Delta G is less than zero. This is the condition we have. I'm just giving you a brief overview of the entire chapter, right? So delta G is less than zero is the condition for the feasibility of reaction. Question is, how would we get this? Like why delta G is less than zero for feasibility of reaction? So all these things we will be understanding in this chapter. Deals with the motion or flow of heat. How heat flows when you have an object at 100 degrees Celsius and another object at, suppose, 50 degrees Celsius, 10 degrees Celsius, whatever. If you connect these two objects with a conducting wire, then what happens? Heat flows from the temperature, higher temperature to lower temperature? Yes or no, right? So the, so the driving force of the flow of heat is what? The driving force is the difference in temperature. Heat always flows from high temperature to low temperature till the temperature becomes equal in the two objects, correct? This is what the heat is. Is this the only way by which heat can flow or energy can flow? This is not the only way, right? Another way is what we can also do some work on the system, right? We can compress it, we can expand it, we can do many more things in order to exchange the heat from this system and other system or surrounding whatever you say, correct? So all these understandings, all these kinds of understanding we are going to have in this chapter, okay? So like I said, we are going to see, discuss or you know, use a lot of different, different terms here in this chapter. I hope you all have the understanding of this entire chapter, what we are going to deal with, understand here in this chapter, okay? So next is we need to first understand all those terms which we will be using very frequently in this chapter or in the coming session of this chapter, okay? So we are going to understand first of all the terms involved in this. So all of you, write down the heading first, the terms involved. So I guess all of you have the join, okay, I think all of you are joined now, fine. Terms involved, okay. So the first term you write down all of you is system. What is a system? What is a system? System is anything, anything around yourself, okay? It is anything, yes, under thermodynamic study or under investigation or you know, under operation we can say. So system is what? System is anything which is under investigation, okay? Thermodynamic investigation. Is anything, in short, I am writing down all these definitions, okay? It is anything which is, which is under observations, under observation or investigation, whatever we are looking at, investigation, okay? It is a part of, it is a part of universe, okay? I will explain this, what is system? Let me just write down the definition first. Second one is surroundings, surroundings, okay? What is a surrounding? Surrounding is also like, you know, it is anything a part of universe, okay? Universe excluding system, yeah, that's correct, okay? So we can also say all other matters, all other matters or simply all matters also you can write, all matters which interacts with, interacts with system is called, is called surroundings, is called surroundings. It is also a part of universe, part of universe, right? This way is very simple, right? Suppose, you know, I am taking the class, correct? And if I ask somebody, okay, you have done the homework or not, then that particular guy becomes a system for me. Yes, Prakul, any doubt? You see now, Prakul becomes system for me and all of you are surroundings, okay? Let me just check. Oh yeah, by mistake, no problem. So whatever is under consideration, okay? You are sitting in the room and you have pen in your hand, right? So if you're considering the pen for a moment, so for that moment, pen becomes a system for you and all other things in the room is soundings, okay? It's very simple, you can understand. Okay, if I take one example here, you see, this is the entire universe, right? This is the entire universe we have. And in this universe, we have one, I'll just change the color. We have suppose one container present, right? In this universe, we have one container and in this container, there are some gaseous particles present. So this entire thing is universe, right? The entire thing is universe. This gaseous particle, if I'm talking about this gaseous particles, this becomes the system for me. And in this universe, you just remove the system, whatever we are left with is surroundings, surroundings, okay? This orange wall that you see, the wall of the container, okay? This wall is nothing but the boundary. It's like the wall of your room is the boundary for you, right? So you are the system, wall becomes the boundary, and the entire house is the universe. This is the surroundings and the entire thing is the universe, right? So surroundings and systems collectively gives the entire universe, okay? It contains everything. Universe contains everything, surrounding systems, boundaries, everything, okay? Now you see this boundary? This boundary has different, different types. And on the basis of this boundary, the types of boundary, okay? You can think of the exchange of energy or heat over there, okay? For example, you see, the types of boundary, if I tell you, boundary can be fixed. We can have fixed boundary, like you see the room in which you are sitting in, the wall is fixed. So we have a fixed boundary, okay? We have fixed boundary. We can have movable boundary. So boundary can be movable also, right? Example, I'll give you. Apart from this, we can have, we can have real boundary, right? We can think of real boundary. Real boundary is fine. We can also have imaginary boundary, imaginary boundary. And apart from this four, we have two more types of boundary. One is adiabatic, adiabatic, and the last one is, and the last one is diatomic. Let's copy this down one second. Just give me a second. Yeah, done. So fixed boundary, you understood what is a fixed boundary? Movable boundary is the boundary which can move, right? Suppose we have a piston-cylinder system, and we will take this example very frequently, piston-cylinder system, right? You must have seen the air pump, right, which we use to fill air into the, you know, the bicycle, right? The air pump. Balloon also, you can see the balloon pump that we have. Yeah, that's also fine. So we see this piston-cylinder system is something like that, okay? So we have a cylinder, and this cylinder is fitted with a piston, right? This cylinder is fitted with a piston. I'm just trying to draw the rough diagram of it. This is the piston we have, for example. Now, this piston can be fixed, can be, you know, movable also. If you clamp this fixed piston over here, it is fixed. But if it is not clamped here, then you apply pressure, the piston can move up and down. So it is the movable boundary we have. Okay? Real boundary is the boundary which you can see, which you can feel, correct? The wall of your room, the real boundary. Imaginary boundary is what? Suppose this is the atmosphere, right? We have this is the atmosphere, the entire atmosphere. In this atmosphere, we know there are several gases, right? Oxygen, methane, nitrogen, hydrogen, many things are there, many gases are there. But you cannot see those gases, right? But you know, okay, oxygen is present over here. So oxygen, gas will have certain radius. And according to the radius, it will occupy a certain volume, correct? That volume or the boundary you cannot see, but you can understand that, okay, it is, this is the volume of oxygen gas. Oxygen gas is present in this volume in that atmosphere. This is the imaginary boundary you have, which you cannot see, which you cannot feel, you cannot touch, right? That is imaginary boundary. What is an adiabatic boundary? Any idea? Adiabatic boundary? Destructive. What is that? Yeah, adiabatic boundary is the one which does not allow heat to pass through, okay? No exchange of heat. Heat we represent with Q. So delta Q, if the boundary is adiabatic, delta Q is zero. No exchange of heat, right? However, we do not have perfectly or ideal adiabatic system. We cannot have. But the best example we have is the example of thermo flask, right? That we use to keep, you know, food or, you know, any tea or anything to keep warm those things, right? Thermo flask that we have. These are the adiabatic boundaries, okay? Best possible examples. Diathomic is what? Diathomic is the one in which the flow of energy through which the flow of energy is possible. Flow of heat, flow of energy is possible. So this is the types of boundary we have, okay? Yeah, understood. So just you need to know the definition, nothing much, okay? Just you need to know the definition and that is it. You won't get any question on this. You may have the application of this if in the question it is given that, you know, suppose the boundary is adiabatic. So adiabatic boundary, you should know what happens in adiabatic boundaries. You should know there's no exchange of heat. Heat exchange is not possible. That kind of understanding you must have, okay? Nothing else. So we have understood system, we have understood surroundings, we have understood the different types of boundaries we have and we know system and surroundings it collectively gives and surroundings it collectively gives the universe. That's why we say both are the part of universe. If the boundary is fixed and, you know, the wall is adiabatic, fixed and adiabatic, then if it is fixed, then obviously work done is not possible, like pressure volume work done is not possible, right? So heat flow is not there. Heat flow is not there in that case. Fixed and adiabatic, no heat flow. Since it is adiabatic, so heat exchange is not possible and since it is fixed also, so you cannot do work on it. There's no volume exchange, right? Volume change. So work is also not there. So hence the heat flow is not possible for fixed and adiabatic. So in fixed, we can do heat exchange. No, fixed and adiabatic heat exchange is not possible. Fixed and adiabatic heat exchange is not possible. And when I say heat exchange, heat exchange between system and surroundings, obviously within the molecule, in the gaseous molecule, heat exchange will be there, right? But not with system and surroundings. If the wall is adiabatic, right? But it is not fixed, piston is movable, then work done is possible. You can do some work. Some expansion compression is possible. And heat may get exchanged in the course of work done, right? The work that you are doing. So if it is fixed and adiabatic, no heat exchange, understood? Now you see different types of system, different types of system. The first one is open system. Open system, you won't be able to understand the open beaker you have, right? So if you have an open beaker, so mass as well as heat exchange possible, correct? Matter can also go out and come, right? So mass exchange possible, heat exchange obviously possible. So it is an open system. We have an open beaker, right? So there's an heat exchange and mass exchange, both possible here. Heat we represent with q and mass is suppose m we have. So both are not constant in this case, right? So heat, q is not constant. It is getting changed, getting exchanged. It's not constant. Mass is also not constant. Second type of system we have, it is closed system. It is only closed, right? It is not mentioned that the wall is adiabatic. It is not mentioned. It's just a closed system, right? So in the closed system, what happens? You have a beaker, closed beaker like this. It is a closed system. So since across the wall or through the wall, heat exchange is possible, right? Through the wall, heat exchange is possible, right? You must have seen when you boil water and you take that vessel in your hand, you feel warm, right? Because heat exchange through the wall of the vessel is there. So you can feel heat outside, correct? So that is what the heat exchange possible here. So in this case, what happens? q is not constant. Heat exchange is there, it's possible. And n is constant. Mass is constant over here. Whatever inside, it is there inside only. Mass is constant, okay? No mass exchange. That's why it is mass constant, right? No mass exchange. What is the third type of system we have? Third type is isolated system, right? What is an isolated system, could you explain? Isolated system is the one which is not interacting with the, you know, the surroundings. It is just present in the surroundings but not interacting, okay? So there's no exchange of heat. There's no exchange of mass. So q and m both are constant here. q is constant. So for isolated system, for a system to be isolated, system must be close, isn't it? A closed system can be isolated system, right? A closed system or other way, if I say. An isolated system is a closed system but a closed system may or may not be an isolated system, right? This closed system, it will be an isolated system as well if you make this boundary adiabatic, right? If the boundary is adiabatic here just a second. If this boundary is adiabatic, if you do some arrangement here so that heat exchange is not possible, then it will be an isolated system, right? Difference in isolated and closed system you must understand, okay? If this is the condition we have, it is closed. If this is the condition we have, we preferably write isolated. If you write closed for this, it is not true. You cannot say, sir, this one is closed. So it is a closed system also. No. For this, we have a particular definition. It is an isolated system, right? So we cannot say this is closed. So isolated system, what happens in this, it does not interact with, does not interact with, with surroundings. All of you understood this? The definition of the three because this definition, the understanding of this definition is important, okay? On the basis of this, you may get some true-false statement, okay? You must have this intense standard true-false question, whether the statement is true or false. But here also, I'm going to give you six different questions. You just have to mark true or false, right? True-false statement based on the definition of the three types of system that we did just now, okay? So write down the heading. Can I go to the next slide, all of you? True-false statement. First question you write down. A closed system always have constant volume. I would request all of you write down the question first and then give you answer in one shot, okay? One true, second false, third true, like that you can say. Second one, neither heat nor matter is exchanged, nor matter is exchanged. Then the system must be isolated. Then the system must be isolated. Isolated system, system will be a closed system, will be a closed system. Fourth one, a closed system, closed system must be an isolated system. In the last two we have, fifth one, an adiabatic container, an adiabatic container fitted with movable adiabatic piston, movable adiabatic piston will form an isolated system. And the last one, an adiabatic container, an adiabatic container fitted with rigid adiabatic piston will be an example of, will be an example of closed system. One more thing, let me tell you. I have done the same question in the rest, the other two batches also, okay? And both the batches, I got maximum four correct. So four question is the maximum, no question that have got correct. More than four, none of them have given the answer, correct answer. So let's see what happens today here. All of you give it a try quickly. Okay, done. Okay, let's discuss this. First of all, I'll tell you the answer. Okay. Yeah. The answer is false, false, true, false, false. And the last one is also false. How many correct? How many correct answer you got? Okay, three, then four, four. More than four, anyone? More than four, anyone? No. Okay, Lavanya got five. Very good, Lavanya. Very good. Titik Shah got five. Very good Titik Shah. So we got five total correct answers. Okay, Lavanya and Titik Shah. Very good. Let's see, we'll discuss this. All these questions are based upon the simple definition that we did just now. Okay. See, the first question is what? The first question is a closed system always have constant volume, not possible. The boundary is not fixed. If the boundary is movable, then constant volume is not there. So definitely the first one is false because we can have, we can have movable boundary. Okay. Piston cylinder system where the piston can move up and down. Correct? Okay. First one is false. Neither heat nor matter is exchanged. Then the system must be isolated. Is it neither heat nor matter is exchanged? Then the system must, we cannot say, maybe may not be. Okay. But we can say it is a, if suppose boundary, another thing is not fixed, then it is possible that we can do some work, work done possible on the system or by the system. And hence in that way, a heat exchange is possible. Isolated system is not possible, right? Because work done is there. Through work done, heat exchange is possible. Isolated system will be a closed system. Yes, that's correct. For a system to be isolated, it must be closed first. Right? So this one is true. A closed system must be an isolated system. Cannot say that. If the wall is not diatomic, is not adiabatic, wall is not adiabatic, boundary is not adiabatic, then heat exchange is possible. System is closed, but heat exchange is possible. But for isolated system, we know there's no heat exchange, there's no mass exchange, right? So with diatomic wall, diatomic boundary, if it is there, then this statement is not correct. Okay. Last two. An adiabatic container fitted with a movable adiabatic piston. Okay. You see container as well as piston is adiabatic, means there is no heat exchange, right? Will form an isolated system, right? You see piston is movable, right? It can move up and down. So work done is possible. Work done is possible. Heat exchange possible. Hence it is not an isolated system, right? So statement is false. Isolated system is the one in which there is no heat exchange by any means. Okay? So this is false. An adiabatic container fitted with, we can say this one is the closed system. It is a closed system we have that we can say, not an isolated system. Okay? This one, an adiabatic container fitted with rigid. Now you see the piston is rigid now. We cannot move it up and down. So work done is not possible. Will be an example of closed system. It is not an example of closed system, but it is an example of isolated system. Isolated system. Is this fine? Yes. Isolated system for the system to be isolated, it must be closed, but it is not an example of closed system. It is an example of isolated system, right? There's a difference in closed and isolated system. In closed system, there heat exchange is possible. Isolated system, heat exchange is not possible. So here if you write down to the closed system, but heat exchange is not possible because the container and the piston both are adiabatic. So, so closed system is not this one. Okay? See there are two things. We are not defining closed system since it is a closed container. Understand it carefully all of you, Krakul and others, right? Close system is not the one which is closed, right? It blocks to close, that system is not a closed system. Definition is what? Definition is for closed system that heat exchange is possible. Mass or matter exchange is not possible. This is the definition we have, right? So you should not think, mainly you know what happens. Students, they start thinking about it. Okay, the boss is closed. It must be closed system, but that is not a thing. Close is defined when heat exchange is there. Mass exchange is not there. When heat mass both are not getting exchanged, then it is an isolated system, right? So this is an example of isolated system, not a closed system. Did you get it? All of you type in CLR if you understood it quickly. Yes? So don't get confused that the box is closed. So it is a closed system. It is not like that. Definition, you just go by definitions. Yeah. Okay. Fine. So this is the first thing that you should know, a closed and isolated system, correct?