 Last of the formula we have in case of write down when there is a phase change this is important daily question ask you guys in case of phase change write down first delta S of fusion fusion means what delta S of fusion is equals to the enthalpy change for this process delta H of fusion divided by the temperature at which the melting is taking place which is the melting point right. So, fusion is melting. Basically, we write down here the energy change divided by the temperature at which the phase is taking place right of vaporization what we'll write delta H of vaporization divided by the temperature this temperature is what should be the boiling point this is what melting point delta S of sublimation Yeah, so that is equilibrium and equilibrium will be 0 and that's why we get this formula right equilibrium phase 3 energy is always 0 ok sublimation this by T right on this question of liquid water is 75.6 joule per mole Kelvin while the enthalpy of fusion of ice is 6 kilo joule per mole. What is the smallest number of ice cubes? What is the smallest number of ice cubes at 0 degrees Celsius? What happened? Each containing 9 gram of water needed to cool 500 gram of liquid water from 20 degrees Celsius to 0 degrees Celsius. Ice cubes at 0 degrees Celsius each containing 9 gram of water needed to cool 500 gram of liquid water from 20 degrees Celsius to 0 degrees Celsius. Have you done this question? No, this one, this one. So yes sir, it's a scientific process. Have you done this question? Yes sir. You need to find out work done in this process. I don't think we have the negative 40. What is the work done in this? Work done in this process will be work done from A to B plus work done in B to C. This is the work done here. You say this BC and AD is isocoding, right? B to C and D to A is isocoding. So work done will be 0. That volume is constant. What? A to B, what is the process? It is isobaric. It is also isobaric, right? Concentrate pressure is 10 and 2 respectively. So here pressure is minus 10 external pressure into Jn volume is what? 9 minus 3 plus here it will be minus 2 into 3 minus 9. Minus 60 plus 12, that will be minus 40 here. Unit is what? Unit is 80 of liters. And when you multiply this by, it will be Jn, right? This is one way to solve this question. Another way is what? In PV axis, PV graph, area under the curve is nothing but the work done, right? So what is the area of this rectangle? Length into breadth, right? This is 8 and this is 6. That is 48. Directly if you find out area, you will get the work done, the magnitude of the work done. Now you see the process is cyclic, it is anticlockwise, sorry clockwise. It is clockwise. So clockwise is always work done by the system, right? So clockwise is work done by the system. The magnitude is this, since it is by the system, so we have to introduce one negative sign here. 48, 8th liter again the unit is. So suppose we do the same but anticlockwise. Yes, yes, yes. This will be positive, this will be negative. See actually this is the theory, how do we get, we are getting negative, that's why I solve this. Negative sign or the by the system. So what we can, the theory is what? If it is clockwise, then by the system. That's how we do it. First question, what is the answer? 40, 49. 1, 4. Okay, how do we solve this question? Options are 1, 7, 14 and none of these. Okay, how many of you have solved this, the first one? 1, 2, 3. Sir, how do we solve this? Sir, I want to solve it. Sir, you want to solve it. Sir, you want to solve it. You'll write properly. Oh, I won't write it. I need the value. You need to explain. What value do you need? I can't remember. I'll give you the question. The specific heat is off. Question number 80. Question number 80. 75 points. I'll take attendance by then. Who is present? I don't know what you're trying to write. I don't know what you're trying to write. Cherry, let me write. I will write. Don't put this on the board. Yeah, that's all. I think he's present. I think he's present. No, I think she's present. Anush is present. Anush, Shadraniya, Drog, Harris, here, Ishan. Ishan Harris is present. Last day, I was getting an upset. Varun, Varun, 42 kilos you like it. 42 kilos. Actually, it is a little bit of a dance. Yeah. Because, you know, the scale of the picture is glib-like. How bad does it look? It is just like a gardener. Did you understand this? Kyaalikha, I did not know. I don't know what it is. It is basically it is MS-1030. This formula, you know, MS for N is 1030. N is the number of moles 500 by 18. S value is given. 1030 is 20. You'll get this. 42 kilojoules per inch. Okay. One more question you write down first. This question. Write down 10 moles of an ideal gas. 10 moles of an ideal gas. 10 moles of an ideal gas. Confined to a volume of 10 liter. Confined to a volume of 10 liter. Is released into atmosphere at 300 Kelvin. Is released into atmosphere at 300 Kelvin. Where the pressure is 1 bar. Find out the work done by the gas. So what was the temperature? 300 Kelvin. 10 moles, 10 liter, 300 Kelvin, 1 bar pressure. It is not. The line is released into atmosphere where the pressure is 1 bar. What is the next chapter we have to start? No. No, no, next class. So we have to do all those different types of things and help. Yes, that is the next class. This is the next class. This is the next class. That is what I do. Minus 240 liter atm. 240 we do not have. Minus 49, 59, 39, 20. V1 is given. V2 you find out. And then we get the V. V1 is 10 liter. V2 we need to find out. And for that number of moles, pressure, temperature, everything is given. We have to find out. 240, is it? No. 240. So 240. So it is 3,012. 250. It will be 20. That is the circle. Yeah, it is 1 bar. The pressure is 0.5. It is exactly 1 bar. It will be 10 to 5. It is not exactly. It is in 1 bar. Yeah, 1 bar. It is 1 bar. It is 10 to 5. So all moles are 1 bar. No, 0.0. 1 is 5 bar. It is correct. It is 100 liter. It is 0.08 liter. It is 1 liter bar, right? Yeah. It is fine. So it is 240. Yes. So, vector is minus p delta v. What is the pressure given? 1. So minus 1 delta v is... What is liter? R liter at most. R liter at most. Okay. It is at most. So what is R liter at most? It is the same. The bar is at most in 0.3 liter. The bar is... at most we will be able to do it. The bar is... At most we will be able to... The bar is 0.1 liter. 0.4 liter. So, sir, let's take the R as 1.5 liter. That also... We have to find the... We can write it as 1.4 liter. So we have to find the... 1.5 liter is 0.3 liter, right? This is also we are not getting. But when you take this value, as a one more digit because it is. Then you will get 240, now you are getting 0.083 according to the option you are getting 239 which is given in the. 240 you are getting. 240 is all close to running. Options are 249 to 9229. Okay, so one last thing right down. Sir, how is pressure one sir? One bar it is given. Sir, pressure one. One bar it is given. Sir, pressure one. Yes, so formula is P excellent right. Excellent pressure. Excellent pressure one. One right down one last thing. Statement of second law of thermodynamics. Statement of? Second law of thermodynamics. Closest statement. Write down it is impossible to construct a machine. It is impossible to construct a machine with 100% efficiency. It is impossible to construct a machine with 100% efficiency. Or next you can write down or write down anything and then next you can write down. It is impossible to convert heat into work without any compensation. It is impossible to convert heat into work without any compensation. Complete conversion basically is not possible. Another one you write down in terms of improperly. This is important. It also states that. Sir, but that is what you said. Sir, an isothermic delta u is 0 and h is equal to minus 0. So that is then. Isn't that contradictory to this? What? Delta u is 0. So when we said w is equal to minus q. Correct? That is conservation of energy. No sir. The second law puts limitations on the first law. That is what. That is conservation of energy. And then we have second law which says that. Complete conversion of heat into work is not possible. So we have some drawbacks in the first law. We have some drawbacks in the second law. Second law basically tells us the first law is wrong. Yeah. Second law is that is what you said. What is the measurement of the first law? Write down next into this. It also states that the entropy of the universe increases in a spontaneous process. It also states that the entropy of the universe increases in a spontaneous process and remains unchanged at equilibrium. So delta s of the universe or delta s total. Universe means delta s total. It is equals to delta s of the system plus delta s of surroundings. So what is surrounding the universe? Surrounding. See system plus surrounding gives you universe. And delta s universe total entropy. This will be greater than 0 for this spontaneous process. And delta. See universe and total same thing. Delta s of universe will be 0. This condition is at equilibrium. So next class we will see the significance of Gibbs free energy. We will finish this chapter thermodynamics. And then we will start thermochemistry. Thermochemistry involves only definitions. Enthalpy of formation, combustion and all. But that is important now. We will do that in thermochemistry. Okay. Thank you.