Lecture 37

We will start the lecture 37, today's topic will be free energies of solid solution and liquid solution and regular solution approach and phase diagrams. nothing but chemical potential, GA bar, GB bar, chemical potential or partial molar free energy. Fine. and regular solution approach and phase diagrams, and we will start the lecture 37, today's topic will be free energies of solid solution and regular solution approach and phase diagrams. So, we will start the lecture 37, today's topic will be free energies of solid solution and regular solution approach and phase diagrams. Again, if this equation, rather not this one, if I compare this equation and this equation, then I can write, I am comparing these two and clubbing them, GA naught plus R, I can write like this, right? Again, if I compare this equation and this equation, then I can write, GB bar, GB plus equal to GB naught plus RT ln AB, I can write like this, right? I can write like this, right? the equation. So, I am comparing these two and this one. I am comparing these two and this one. So, I am comparing these two and this one. And then if I compare, I can write like this, right? B in A, B in A, B in A. 1, condition 2, condition 3, condition 4, condition 5, condition 6, condition 7, condition 7, condition 8, condition 9, condition 10, condition 11, condition 12, condition 13, the So, we can write this as 1 minus b square plus 1 minus b square, so this is equal to to 1. Activity to 1. A B equal to x B, mole fraction of B equal to activity of B. B in A. B in A. B in A. This equal to less than 0. Del H mix less than 0. Ln gamma B less than 1. So, less than 1 gamma B less than 1. A B less than x B. To x B less than A B less than activity of B is less than mole fraction of B. gamma B equal to R T. And tends to 0, exponential R T. Slope fine, constant, this R and T. All constant, all constant. This should be also constant. Slope gamma B less than 1. And, if I see that every value on this point, if I see every value on this line for dilute solution, then it will be a b less than x b. Because, x b is varying with a. And, here I see that when this condition comes, I see that the activity of b in that solution, mole fraction of b is less than that. So, this is called Henryan, this follows Henryan law. We will discuss this again. This line follows Henryan, this line follows Henry's law. Henry's law of solution. And, if I see this condition, when it happens? When del h mix is 0, constant straight line, constant slope and gamma b equal to 1. So, slope, I say this mix 0. This is Raoult's law of solution, fine. Third condition, gamma omega is greater than 0, del h mix greater than 0, this is Raoult's law of solution. Learn gamma b greater than 0. Gamma b would be greater than 1. Slope and gamma b would be greater than 1. So, this is Raoult's law of solution, fine. So, this is Raoult's law of solution. So, this is Raoult's law of solution. So, this is this is pure A, this is pure B, eta hoche 1, eta hoche A, A equal to x A or jokhoni A A less than 0, omega ta jokhoni 0 hobe, A A less than 0, omega ta jokhoni 0 hobe, A my A greater than 1 slope, it is less than 1 slope, it is less than 1 slope, x A tends 1 slope, it is less than 1 slope, it is less than 1 slope, x A tends to 0, it is less than less greater than 0 activity of A mole fraction of A and omega less than 0 activity of A mole fraction of A and extreme low concentration of A in B straight line slope gamma slope And from here we can see how Henry's law is followed. That means Henry's law will be followed only at a time when the concentration of a solute is very less in solvent. And another condition for following Henry's law is that del H mix is non-zero value. Either less than 0 or greater than 0. Then only this will be possible. So, that means, I am seeing that the pattern of a solution is changing, if my del H mix is positive or negative. If it is 0, then in a constant slope, the activity and mole fraction will be equal. That is A in B or B in A, whatever it is, it will be like that. So, here we could understand the pattern of a solution. Henry's law follows this, Raoult's law follows this, and in case of A, this line follows Raoult's law, and these two lines, this and this, these two follow Henry's law. So, we understood this. Now, we have to solve a solution. So, the temperature decreases, phase separation, miscibility gap, liquid solution, solid solution, liquid solution, liquid single phase, liquid single phase, solid solution, liquid single phase, solid single phase, liquid single phase, solid single phase, solid single phase, solid liquid solution. So, liquid solution liquid solution 1 or it is solid solution 2. Liquid solution liquid solution 1, liquid solution 2. So, liquid solution liquid solution 2. So, liquid solution liquid solution 1, liquid solution 2. So, liquid solution liquid solution 1, liquid solution liquid solution 2. So, liquid solution liquid solution 1, liquid solution 2.