 Hello guys. Good evening. Yes. Oh, or a fine. Yeah. Yeah. If you want, you can upload to, uh, on class also. Uh, you have to check once tomorrow you can upload. Okay. Not today. Tomorrow you can upload. Okay. So where were we in the last class? Yeah, that's what today I'll do that and you can upload it tomorrow. Okay. Actually, I think we had done side last class, right? Yeah. Preparation and all. Okay. Have we discussed sodium peroxide and a two or two? Yeah. Preparation of any watch we have done so we'll have it in the properties properties of any watch. Yes or no. Done, right? Okay. Yeah. So next write down the next compound we have. That is sodium peroxide. All of you write down the heading and a two or two. Okay. Sodium peroxide we are going to start with. Write down. See, on industrial scale, it is prepared by the reaction of NA with O2. Like you see two NA plus O2, the temperature we use around 620 Kelvin and it converts into Na2 and O2 here. Atmospheric oxygen we are digging. It is heated with the air which is free from moisture and carbon dioxide. So it reacts with atmospheric oxygen and converts into Na2 O2. Some properties of this, if you see, usually the sodium peroxide is, you know, the pure form of this is colorless powder. Pure form is colorless powder. But due to the presence of superoxide, due to the presence of sodium superoxide. Sodium superoxide that is NaO2. It is faint yellow, slightly yellow in color. It is a powerful oxidizing agent. It is a peroxide. So powerful oxidizing agent, powerful oxidizing agent in contact with one reaction of example of the cell write down. You see, if it reacts with 2Cr OH twice plus the peroxide ion 3O2 2 minus peroxide ion is this. It converts into 2CrO4 2 minus plus 2OH minus plus 2H2. One more important property of this is NaO2 gives this O2 2 minus ion. You see, Na2 O2 we have, it gives 2Na plus O2 2 minus. So this O2 2 minus we are using here. Yeah, done. Third property, you see, third property is Na2 O2, Na2 O2 in contact with moist air turns white, turns white due to the formation of Na2 CO3, due to the formation of Na2 CO3. If you look at the reaction here, the reaction is 2NaO2 Na2 O2 plus 2H2O. It converts into 4NaOH plus O2. This is the first step. Next step is NaOH reacts with CO2 and converts into Na2 CO3 and H2O. So because of this presence only, it becomes white. Another point, Na2 O2 is diamagnetic in nature. Na2 O2 is diamagnetic in nature. One very important reaction of this is on reaction with cold dilute H2SO4, cold dilute H2SO4, it gives hydrogen peroxide, it gives H2O2. If you look at the reaction here, Na2O2 plus H2SO4 gives Na2SO4 plus H2O2. This one is cold and dilute. One second, Brugha. Previous slide, right? You haven't written? This is the one. See, with cold dilute acid, it gives hydrogen peroxide. If acid is hot over here, hot concentrated, in that case it eliminates or it evolves oxygen gas. On reaction with acid, it evolves oxygen O2 gas. So the reaction is Na2O2 plus H2SO4. This gives Na2SO4 plus H2O and oxygen gas releases. So this property you must remember. Right on the next compound we have sodium bicarbonate, NaHCO. See, I'm doing only the important one, okay? NCRT you have to revise and these chapters are like you have to mug up, right? There's nothing to understand. So you have to memorize things, correct? So I'm doing the important one, but NCRT thoroughly you have to go through. Okay, line by line you have to study. Sodium bicarbonate is NaHCO3. We also call it as sodium hydrogen carbonate. It's also known as sodium hydrogen. This is the common name of this one is we also call it as baking soda, okay? Common name is baking soda. How do we prepare it? It is prepared with the help of Na2CO3. So what happens? We take Na2CO3 and we dissolve this in a saturated solution of carbon dioxide. So we have CO2 and H2O and in this you dissolve Na2CO3. It converts into two molecules of NaHCO3. This is the preparation method we have, okay? This reaction is reversible also means if you heat this sodium bicarbonate NaHCO3, two molecules of this, if you heat this at around 6 or 375 Kelvin, it converts into the formal product which is Na2CO3 plus CO2 and H2O. Hence we always say that we also say that on heating sodium bicarbonate evolves carbon dioxide. Some properties of this, you see, it is a crystalline compound. Exist in powder form. We also call it as crystalline powder. It is a crystalline powder. Its solution is alkaline in nature, alkaline in nature. Why it is alkaline? You can understand. I'll discuss this first. You copy down this. Okay. Now, why it is alkaline in nature, you see, it is a salt, right? NaHCO3 is a salt. How does this salt form? If you take an acid, a base like NaOH and an acid, suppose I'm taking H2CO3, right? This acid, if you remember, it is a, it is carbonic acid, carbonic acid, weak acid it is. Okay. This is hydroxide, a strong base. So when this reaction takes place, mono-basic acid, if it behaves, it forms NaHCO3 and H2O. I said mono-basic acid, it behaves. It doesn't mean that it is mono-basic acid. H2CO3 is a di-basic acid, but it forms NaHCO3 when it behaves as mono-basic. Yes, it behaves as mono-basic to form NaHCO3. So this salt, you see, NaHCO3, it is a salt and we say it is a salt of a strong base and weak acid. Since base is strong, so this will have the basic property dominating here. That's why the solution is alkaline. Okay, one last compound we'll see for sodium, it is sodium carbonate Na2CO3. Na2CO3 have various hydrated forms. Na2CO3, this is the anhydrous form we have. So it is various hydrous and anhydrous form. If you look at this example, if I simply write Na2CO3, so it is the anhydrous form we have. If you write Na2CO3.H2O, it is monohydrate form, monohydrate. If you have Na2CO3.7H2O, it is heptahydrate form, 7H2O. Heptahydrate, if it is Na2CO3.10H2O, it is decahydrated form. And the most important one is the decahydrated one because this we call it as washing soda. Then, okay, the preparation one method we have that is Solve ammonia soda process. Preparation, name also it is important. The process name is Solve ammonia process, ammonia process or we also call it as Solve ammonia soda process. Both are same thing. Ammonia soda process, write down in this process, write down in this process, CO2 is passed through, passed through. Brin solution, brin solution means water plus salt. Brin solution saturated with ammonia, saturated with ammonia. And sodium bicarbonate NaHCO3, sodium bicarbonate forms. So, the reaction here is we have NH3H2O and CO2. This gives NH4HCO3 plus H2O, ammonium bicarbonate. NH4HCO3 is ammonium bicarbonate. This ammonium bicarbonate in the next step, this first forms NH4HCO3, then it reacts with the brin solution. Brin solution means water plus salt we have. So, it takes NaCl from the brin solution and it converts into NaHCO3 plus we'll get NH4Cl. We'll get NaHCO3, this will precipitate. This NaHCO3 will heat strongly and it converts into Na2CO3 plus H2O. You know, till here it's fine but the problem is what? That this Na2CO3 that forms, it is highly contaminated with ammonium salt, right down here. It is highly contaminated with, contaminated with ammonium salt. To remove this contamination, what we do? To remove this contamination, we allow this to react with aqueous solution of carbon dioxide. So, it is purified by blowing carbon dioxide through its aqueous solution. So, what we have next? This Na2CO3 further in the next step, it is allowed to passes through an aqueous solution of CO2, which further this converts again into sodium bicarbonate, NaHCO3. And then when we heat this strongly, this converts into Na2CO3 plus H2O plus CO2. So, this after this step, the sodium carbonate that we get, it is fairly pure, okay. So, this is the way we prepare NaHCO3 here, properties you write down. It is a white crystalline solid, exist as decahydrated form. Its temperature based reaction is very important. Look at this reaction here and for this reaction, you need to memorize the temperature. For example, you see if you have the decahydrated form Na2CO3.10H2O and if you heat this below 375 Kelvin. Or 370 Kelvin. It converts into monohydrated Na2CO3.H2O and 9H2O will eliminate here. Further, if you heat this, temperature is more than 375 Kelvin. It converts into Na2CO3, the anhydrous form and water eliminates. So, this anhydrous form is also known as soda ash. Write down this soda ash will have few reactions here, important reaction. Write down soda ash or write down like this Na2CO3 on reaction with, on reaction with silica. Silica is SiO2. On reaction with silica, it forms sodium silicate. The reaction is Na2CO3 plus SiO2 converts into Na2SiO3 plus SiO2. This is sodium silicate, sodium silicate and it is also known as water glass, water glass or soluble glass. Copy this down, we will discuss some compounds of potassium, only one or two, not much. Write down next, some compounds of potassium. The first one we write down here, potassium hydroxide, COH. See the preparation of potassium hydroxide you see, it is prepared by the reaction of slag lime that is CaOH whole twice with K2CO3. We will see how to prepare potassium carbonate also. It converts into CaCO3, it precipitates out and forms 2KOH. It can also be prepared by electrolysis KCl, aqueous KCl actually. So the reaction at, it is similar to the electrolysis of NaCl. Okay, so at cathode, the reaction is 2K plus plus 2H2O plus 2 electron, it converts into H2 plus 2KOH. At anode, the reaction is 2Cl minus converts into Cl2 plus 2 electron. This is what we get at cathode. Then, and one more thing is properties very much similar to NaOH. Okay, so we have the same thing here. Next write down potassium carbonate, K2CO3, K2CO3. This we also call it as potash or pearl ash, also known as simply potash or pearl ash. Write down, it is prepared by, it is prepared by heating potassium nitrate and carbon. So if you look at the reaction, 4KNO3 plus 5C converts into 2K2CO3 plus 3CO2 plus 2N2. Okay, this is one method. It is also prepared by carbonation of caustic potash, which is the reaction 2KOH plus CO2. Carbonation is nothing but the reaction with CO2. It forms K2CO3 plus H2O. Then, one last compound we will see here, that is, we have a general name, we call it as ALMS, A-L-U-M-S, ALMS. Yeah, write down ALMS. So what are ALMS? ALMS are the compounds, and they are the compounds which are the mixture of, mixture of potassium, sulphate, aluminium sulphate, potassium and aluminium sulphate. I did not do anything pradyum, since noise from your site was coming, I muted you, I did not unmute you actually. Yeah, that is for, I think I muted you, that's why you got the message. Anyways, not a problem, so you know it. Right, so ALMS are what? ALMS are in general, these are the compounds of potassium and aluminium sulphate, right, which is dissolved in concentrated water. Right, this kind of compound, we also call it as double salt. Okay. General formula you see, the general formula is, we can write down the general formula is R2SO4.MSO4 whole thrice, M2SO4 whole thrice. Dot 24 H2O, this is the general formula of LM, okay, where R is the, R is the monovalent metal, monovalent metal, like Na plus K plus and so on. M is the trivalent cation, trivalent cation, AL3 plus we can have, Fe3 plus and all these, correct. So if you look at the formula of Potash LM, Potash LM, the formula is K2SO4 dot AL2SO4 whole dot 24 H2O. Understood this, this compound is Potash LM, this kind of compound, we call it as double salt. When you dissolve this in water, it will dissociate in various ions, like suppose if you dissolve this in water, what all ions we get, could you tell me? We get here, in water it dissociates as K plus, I'm not balancing it out, just ions I'm writing it on. K plus you will get, you'll get AL3 plus, plus you'll get sulphate ion SO4 2 minus and water will be there, so water will write down as it is. Like this it dissociates. So this kind of additional compound dot, dot if you have, right. This kind of additional compound we call it as double salt, okay. Three types of compounds basically we have, simple compound like NaCl, S2SO4 type. The second is this and third one is complex compound, which we'll discuss in class 12. This compound is Potash LM, formula also they have asked many times in the exam, so you must remember the formula of Potash LM. Okay, so this is it for this chapter, next we are going to start with group 2, that is alkaline earth metal, okay.