 So next heading you write down will like I said, we'll discuss the extraction of various metals also. What are the different different steps involved and how do we do this? But before going into that, first we'll see the Ellingham diagram. So write down the heading. Ellingham diagram. This is very important for your board exam, school exam, anything. So in this chapter, this is the most important topic we have. Ellingham diagram. Few things you try to understand first, we'll use the concept of thermodynamics here also to make you understand this. Okay. So Ellingham diagram to understand this will use the concept of thermodynamics. So before going into the graph directly, which is there in the NCRT book, if you have your NCRT book with you, you can open it now. Okay. And you can see the diagram. I'll also draw the diagram. But first of all, let me discuss the theory of it. Okay. Like, you know, Ellingham diagram, we all know that for a spontaneous process for spontaneity, what is the condition we have for spontaneity? We have two conditions generally. And that is delta H less than zero exothermic or entropy increases delta S greater than zero. Right. So we can say either the process should be exothermic or it goes towards more randomness. This is the condition of spontaneity. Okay. Now if I write down the relation and the combined combination of these two gives you this delta G is equals to delta H minus T delta S. Right. So overall condition if I write for a spontaneous process, delta G must be less than zero. This we have already done in class 11. Right. This is the condition we have for spontaneity. Now you see to discuss this Ellingham diagram for any oxide formation, for any oxide formation, what we can say that the oxygen gas consumes, right? Oxygen gas consumes. And since the gas particle is getting consumed, so we can say entropy decreases or increases. Tell me delta S oxygen gas consumes and hence entropy decreases or increases. How this increases? Tell me gaseous particles is getting consumed. So obviously the entropy should decrease. Yeah, because the gaseous particle is getting consumed. So entropy should decrease in this. So when the oxide formation, which is one of the steps we have in extraction of metals, what we can say the entropy delta S decreases because the gaseous particles is getting consumed. Right. So M metal plus O2 gas if I write, it forms suppose oxides MO and that is why the entropy decreases. Correct. So when temperature increases, you see here, when temperature increases, then what happens? T delta S becomes more negative. Yes or no? Becomes more negative, right? Because delta S is decreasing, T increases, T delta S becomes more negative. T delta S becomes more negative, hence delta G what? Delta G increases with increasing temperature. All of you understood this. If T delta S is more negative, then this T delta S minus M we already have, this becomes plus and delta G increases. That's what I wrote here. All of you have written this. Can I go to the next space? Tell me. Okay. So now, write down this. The free energy change that occurs, free energy change that occurs when one gram molecule of a common reactant, which is generally we have oxygen is used, free energy change that occurs when one gram of a common reactant is used. When plotted against, when plotted against the temperature, the temperature for a number of reactions of metal, number of reactions of metals forming their oxides. The graph that we get in this way, we get this way is called Alingham diagram. So basically Alingham diagram is the graph of what? Is the graph of delta G, right? Delta G naught versus temperature. In short, delta G naught versus temperature. Okay. Temperature we write here in degree Celsius. Okay. And in which reaction, the reaction in which the metal forms, metal forms metal oxide. In this reaction, whatever the change in delta G naught we have with respect to the temperature, that graph gives you the Alingham diagram. Got it. There are some key features of this diagram. Okay. So first we'll see the diagram here. You also draw this. This axis we have temperature in degree Celsius, 500, 1000, 1500, 2000, 2500. This side we have minus 1200, minus 1000, minus 800, minus 600, minus 400, minus 200, 0 plus 200. Delta G naught, the unit is kilojoule per mole. Okay. All of you draw this diagram. Okay. The first graph here goes like this. This is the graph we have. This graph is for silver, AG, the first one. This is HG. This graph is for C plus O2 gives CO2. This graph is for nickel. This is for iron. This is for chromium. This is for titanium. This is for aluminum. This is for magnesium. And the last one is for calcium. The sharp change, this includes that at this point, magnesium boils. That's why we have a sharp change in the slope. This point similarly, HG boils. Again, I'm telling you this, this diagram you don't have to memorize. Okay. The diagram is not that important, but there are a few things we need to understand from this graph. That's why I have drawn this diagram here. Okay. So what we observe the first thing here, if you see, all of you have done this, tell me. Now the first point, this key features you must remember. Okay. This is important. The first point here is that we observe from this for most of the metal we see, the oxides of the metal. This graph actually, it is the graph of oxides of this metal, chromium, titanium, aluminum. Right. I have written only metal name here, but this actually represents the reaction of this with oxygen which gives the metal oxide. Okay. So first thing that we observe for most of the metals, the Gibbs free energy change, Gibbs free energy change increases with increase in temperature. That is what we observe increases the sharp change in this graph. Next point to write down the sharp change represents the change in state, the change in state when the material melts or or vaporize third point below this line you see below the line delta G is equals to zero below this line delta Z is equals to zero this line. So write down below the is equals to zero line. The oxides are stable are stable because less than zero. And above this line, the oxides are unstable. Unstable means it dissociates into into the metal and oxygen further. So this diagram also gives us the information of oxides of any metal is stable at which temperature. Right. So for this you see approximately for silver oxide, the line this line where this line cuts this delta G is equals to zero line below this line below this point. The silver oxide is stable above this line. The silver oxide is not stable means corresponding to this point this intersection of these two lines corresponding to this point you will have some temperature. Right. So we can say below this temperature the oxides of silver is stable above this temperature the oxide is not stable and it converts back into the metal and oxygen. Right. Did you finish this tell me. Okay. Now in this third point only one note you write down in the third point like what we say that when you heat the oxides of any metal any oxides it decompose into its metal and oxygen. Right. So what we can write here theoretically theoretically all oxides can decompose into metal and oxygen and oxygen at high temperature. Theoretically it is possible at high temperature. But practically from Ellingham diagram but practically oxides of silver gold and mercury oxides of silver gold and mercury are the only oxides are the only oxides which can be decomposed which can be decomposed. At high temperature since it crosses the line delta G is equal to zero line these oxides only crosses and hence that's why we also say and hence this metal can be extracted from the thermal decomposition and then this metal can be extracted from the thermal decomposition. Right. So keep that in mind these three can be extracted by thermal decomposition. Now the next important point we have the fourth point you write down the metals which lie which lie above in Ellingham diagram get reduced by get reduced by the metal which is below which is below. Right. So as you are going down in the Ellingham diagram. Right. The oxidizing tendency oxidizing tendency increases for the metal to get oxidized the tendency is more. Right. As you go above. Right. Bottom to top if you are going the metal has more tendency to get reduced. Right. And the one which is above get reduced by the one which is below. Right. So when you see the Ellingham diagram when you see this Ellingham diagram. So we can say chromium get reduced by titanium titanium get reduced by aluminium like this magnesium get reduced aluminium get reduced by magnesium below this temperature 1500. Okay. Magnesium aluminium get reduced by magnesium below 15 degrees 1500 degree Celsius. Okay. That's how it means. Okay. One note you write down here aluminium aluminium reduces oxides of iron chromium titanium. This reaction is known as is known as thermite reaction thermite reaction magnesium cannot reduce oxides of aluminium above 1500 degree Celsius. Okay. Finish this one.