Lecture 34

We will start the lecture 34, in the last few lectures we have seen that when del H mix becomes non-zero, then what kind of effect it has on the del G mix, we will continue that and we have seen three conditions, one is definitely when del H mix becomes zero, then it is an ideal solution, but when del H mix becomes negative, then the del G mix is continuous downwards, but when I take del H mix as positive, then the magnitude of del H mix and the magnitude of del G mix, then the magnitude of del H mix and the magnitude of del G mix will vary. We have seen in the last class that if the del H mix is highly positive and if the magnitude of T del H mix is more than the magnitude of T del H mix, then we have seen that in the extreme 2 end, in the pure condition, in the pure A and pure B side, we have seen that the del G mix is negative, negative downward, then when we go away from that pure condition, then we have seen that the del G mix moves towards the positive side, and we have seen the reason for that, the reason is that in the pure condition, when it is very dilute solution, then the slope of the del G mix becomes minus infinity. So, we have seen that in the pure condition, when it is very dilute solution, then the slope of the del G mix becomes minus infinity, and when we go away from that pure condition, then the slope of the del G mix becomes minus infinity, and when we go away from that pure condition, then the slope of the del G mix becomes minus infinity. mix is a continuous downward. So, minus T del S mix downwards minus del G del H mix or minus T del S mix a magnitude of del H mix on del H del G mix about G 2 solution free energy. del H mix about G 2 solution free energy about G 2 solution free energy about G 2 solution free energy about G 2 solution free energy about G 2 solution free energy about G 2 solution two to different phase equilibrium phase 1, 1 of composition X B 1 and X B 2, X B 1 equal to in equilibrium with phase 2 of composition 2, composition 2. So, I can write X B 1, X B 2, X B 3, X B 4, X B 5, X B 6, X B 7, X B 8, X B 9, X B 12, a single phase liquid solution So, the main reason for this phase separation is that I had a single phase, and it broke into two phases from the single phase, and to break it into two phases, I created a miscibility gap in the system, because at first everything was miscible, A and B were completely miscible in high temperature, because there I see that the del H mix is always negative, but when I, at all compositions, when I came to low temperature, I saw that slowly the single phase is breaking into two phases, separating into two phases, and to separate it into two phases, a miscibility gap was created in my system. Two different phases were in the same state, that is, solid state or liquid state, liquid form can also be called. a miscibility gap. Fine. a miscibility gap. T equal to T1, T4, T4, T4, T equal to T3, T equal to T2, and T equal to T1. T4 greater than T3, greater than T2, greater than T1. a miscibility gap. So, this is T 1 del S mix minus this is T 2 del G mix this is T 3 del G mix this is del H mix this is del H mix fine. Del G mix del H mix minus T del S mix or T del T 1 del S mix except x A equal to 1 and x B equal to 1 . So, the extreme in the slide downward at a movement of a del G mixer . So, this is T 1 del G mix this is T 2 del G mix this is T 3 del G mix this is T 3 del G mix. So, this is T 3 del G mix this is T 3 del G mix this is T 3 del G mix this is T 3 del G mix. So, this is T 3 del G mix this is T 3 del G mix this is T 3 del G mix this at T 1 and x B 2 T 2 is less than x B 2 T 1 . a contribution minus T del S mix or del G del H mix del H mix greater than 0 and variation of del G mix with temperature variation of del G mix with temperature high temperature T1 x A equal to 1 x B equal to 1 or rather T4 T6 greater than T5 greater than T4 greater than T3 or rather I would consider T4 variation of del G mix with temperature del G mix variation with temperature binary solution Thank you