 Okay. Second type of hydride right now, that is second type of hydride, metallic hydride, which we also call it as non stoichiometric, metallic non stoichiometric, or we also call it as interstitial hydrides. Write down these type of hydrides. These are just informations. Okay. This type of hydrides are formed by are found by adsorption of hydrogen adsorption of hydrogen on the metal lattice. This is adsorption, not absorption. Okay, remember that on metal lattice. It is, which is mostly formed by transition element transition element last point and the properties of these hydrides properties of these hydrides are similar to similar to that of parent metal. See here, these hydrides are hydrides are non stoichiometric. For example, you see, it forms YH2 type, YH3 type, LAH2.87, VS0.56, etc. VH2 also it forms. Okay, non stoichiometric hydrides. Density of these hydrides, density of these hydrides is lesser than lesser than from the parent metal. One very important property we have here. Write down this question they asked many times in the exam. If you see from group in group six, seven, eight, and nine, these four groups of transition element, only one element we have which forms this type of hydrides that is chromium. From group this only chromium forms this type of hydrides, this type of hydrides, and hence from group six to group nine, this we call it as hydride gap. See, in this hydride what happens the hydrogen. It includes into the crystal lattice. So it's volume expands. When hydrogen includes in the previous one it does not affect the, you know, the crystal structure. But here the volume the crystal expands volume increases. So when hydrogen goes into the interstices of the metals, right. So it's volume increases because the lattice expands, and hence overall density decreases. That's the reason. Yeah. Last one you write down third type. That is molecular hydrides, molecular hydrides and covalent hydrides are the same thing, molecular or covert. As I said, it is formed by the P block elements, right, along with that barely man magnesium also forms, okay, formed by my P block elements, and along with P block, we have example of bH2 and mg H2 covalent hydrides forms. Covalent hydrides are covalent in nature because the electronegativity, negativity difference is not that great. Right. In some molecule like HF we have great electronegativity difference, but they have a small size so more polarization leads to covalent activity. Right. Like I said further, this hydrides are classified into three categories. First one is electron deficient. Electron deficient hydrides are those hydrides in which the number of, you know, electrons is less than eight. For example, first of all you see it is formed by the elements of group 13. The three block first is elements of group 13. So the hydrides that we have bH3, AlH3, etc. So if you look at the electrons for boron in this compound, bH3, the electron we have for boron is six electron, less than eight, so it is electron deficient. It contains one vacant orbital here. If you look at the bonding vacant orbital, and hence it has tendency to accept electron. Right. It can accept electron pair. So it has tendency to accept electron pair. Hence it behaves as Lewis acid. Let's write down the second type in this we have b, that is electron precise hydrides, electron precise. Electron precise means which has exactly eight electrons. For example, you see it is formed by, which group could you tell me, by the elements of group. Any idea? Group 14, not two, group 14. So alkali metals, alkaline and metal, so group 14. Okay. So example of this, if you see we have CH4, SIH4, etc. All these molecules you see, carbon has exactly eight electrons, one, two, three and four, right, eight electrons. It is electron precise hydrides. What is the hybridization? What is the geometry? Geometry, shape, same because there's no lone pair, correct? Similarly, the third type we have, that is electron rich. Electron rich hydrides are those which contains lone pair, which has tendency to donate electron pair. So we must have lone pair for this. It is formed by the elements of group 15 to 17. Group 15 also forms, group 16 also forms and group 17 also forms. Group 15, the example you see NH3 has one lone pair. Group 16 has H2O, has two lone pair and group 17 we have HF3 lone pair. So all these hydrides contains lone pairs and calls electron rich hydrides. Since electron pair is present here, lone pair, it has tendency to donate lone pair and hence it behaves as Lewis base. So next the hydrides we have done. Next we will see the another type of compounds we have, that is hydrogen peroxide. What is the formula of hydrogen peroxide? H2O2, okay? First of all, we will see the preparation of it. How do we prepare hydrogen peroxide? This one, two methods we have not much. Preparation, right down from barium peroxide, from barium peroxide, right down hydrated barium peroxide, hydrated barium peroxide. The formula is BAO2.8H2O. Hydrated barium peroxide reacts with dilute H2SO4 to form hydrogen peroxide, okay? So the reaction is BAO2.8H2O. These reactions basically you have to methods, it's not important, but there's no logic into this, you have to memorize this, okay? However, they won't ask these questions. H2SO4 dilute gives BAO4 plus H2O2 plus 8H2. This is the reaction we get. One note you write down, anhydrous, copy down this first, write down anhydrous barium peroxide, anhydrous barium peroxide forms a protective layer of barium sulphate, forms a protective layer of barium sulphate. Anhydrous barium peroxide forms a protective layer of barium sulphate on reaction with H2SO4 and does not allow the reaction to proceed. Okay, so if you use anhydrous barium peroxide on reaction with H2SO4, it will create a layer of barium sulphate on its surface, which prevents the further reaction and hence H2O2 does not form. That's why we do not use anhydrous form but we use hydrated form of barium peroxide. So I'm repeating itself. Anhydrous barium peroxide forms a protective layer of barium sulphate on reaction with H2SO4 and prevents the further reaction. The second method of preparation we have, that is electrolytic process, electrolytic process, write down in this method, in this method electrolysis of 50% H2SO4 sulphuric acid is carried out at low temperature using platinum electrode. So, you have 2H2SO4, which ionizes and forms 2H2SO4 minus and this further oxidize, I'll write down it separately, this further oxidize 2HSO4 minus oxidize into H2S2O8 and the electron comes out, this reaction takes place at anode. In the next step, hydrolysis of H2S2O8. H2S2O8 goes under hydrolysis in the next step and forms H2SO4 and hydrogen peroxide. Yeah, done. Okay, so these are the preparation method, two preparation method of hydrogen peroxide. But questions they do not ask on the preparation method, only one point is important that why we use anhydrous, sorry why we use hydrated barium peroxide to prepare hydrogen peroxide. H2S2O8 is peroxy sulphuric acid, H2S2O8, if you want to see the structure, 6, the structure is this, S double bond O we have and we have double bond O, OH, O, peroxy disulfuric acid, it has a peroxy linkage here. Okay, could you tell me the oxidation state of sulphur here and here, oxidation state I asked, I think, yes, oxidation state is plus 6 on both sulphur atom. I have discussed these things in redox, it's not minus, it's plus 6. Yeah, no doubt in this. Now, so preparation method like I said only that why barium are hydrated barium peroxide we are using for the preparation that reason you must remember. And one thing that you must keep in mind is the structure of H2O2. H2O2 is we call it as open book structure, it has open book structure. Open book structure is this, we have oxygen, oxygen bond and this hydrogen, this hydrogen is connected like this. So you imagine this is the spine of the book, O, O bond, spine of the book correct, and one side is this open and other side is this open. Like one page is this side, one page is this side. Open book structure, each oxygen atom has two lone pair. Okay, the bond angle here, this bond angle equals to this bond angle, both are 97 degree. This bond length is L1 and the bond length here OO bond length is L2, this bond length here is also L1. So bond length of L2 is greater than L1. This you must remember. The name of the structure plus this relation. Why because we have lone pair, lone pair present here so we'll have lone pair, lone pair repulsion. That's why the bond length here increases. Yes, yes, yes, it is important. The bond length L2, this is not important to memorize, L2 the OO bond length we have it is 1.48 angstrom and the OH bond length L1 is 0.97 angstrom. Right, so because of lone pair, lone pair repulsion OO bond length is more than to that of OH bond length. So if you look at this orbital diagram of H2O2, oxygen has 8 electron. One second, I'll go back. What is the hybridization of oxygen, could you tell me what is the hybridization of oxygen in H2O2, SP3 correct. So one S here you see one S and three P will go under hybridization and it forms for SP3 hybridized orbital like this. In which two orbital has two electron and one orbital has two orbital has one electron. All these are SP3 hybridized orbital correct. And similarly we have this for another oxygen atom also. So if you draw this orbital. See this one orbital is this. Another orbital is this. I'm assuming this two orbital has two electron two lone pair. This one has one electron and this one also has one electron. This I have just represented this way in the orbital form. If you talk about the another oxygen atom, which is this. This also has four SP3 hybridized orbital two electron two electron one electron and one electron. So what is this axis. Inter-nuclear axis forms a sigma bond axial overlapping yes or no axial overlapping. So this is how the oxygen oxygen sigma bond forms and you must remember this in this sigma bond SP3 SP3 orbital overlaps and forms a sigma bond. These two bonds are attached with hydrogen. You see hydrogen is this. This orbital with one electron it comes and overlap with this orbital. This is the one electron of it. This forms again a sigma bond. So this is OH bond O bond OH bond. This is what the bonding we have. So here we have SP3 S overlap SP3 S overlap SP3 SP3 overlap. Yeah. So we have a few properties of hydrogen peroxide right now. First one it is colorless and orderless. It is colorless orderless and bitter in test. It's orderless and tasteless. Sorry, bitter in test not tasteless. No. No mother. Then you ask me how do we know that it is bitter in test. Right. Yes. I knew that. Well, you try to find out the property of these compounds. So we'll do some experiment week. No, we obviously need to only test it. You can do that for testing only, but you don't eat it like it's not edible. Correct. Okay. So colorless orderless bitter in test. Right. And it is known as associated molecule due to hydrogen bonding. It is known as associated molecule due to hydrogen bonding. Like wherever we have hydrogen bonding, the molecule is said to be associated molecule because one molecule is connected with others like in water molecule also NS3 also HF also correct. So this is also associated molecule. All those molecules which can form hydrogen bonding with water are soluble in water. Correct. So this one is also soluble in water. No, no, no, it's not nothing is written now. Okay. Right. It is soluble in water. I'll write down since it forms hydrogen bonding. So it is soluble in water. Even we can also say alcohol because alcohol can also show hydrogen bonding with S2S2 and ether. It is a powerful oxidizing agent. It is a powerful oxidizing agent. So if you look at the reaction here, it is a lead sulfide PBS plus H2O2. It oxidizes lead into sulphate PBSO4 and get itself the reduce. If you see this reaction hydrogen sulfide with H2O2, it converts into H2O plus sulphur. Okay. Next slide down. In this only I'll write down one more point. Due to, yeah, it is also, we'll talk about it one second. It is also reducing agent will talk about it. Just a second. Due to its, due to its oxidizing nature oxidizing nature. It acts as a bleaching action, bleaching agent, sorry, decolorizes. Any color, colored material. It produce the nascent oxygen. And in presence of nascent oxygen, this colored material becomes colorless. So this we call it as the bleaching action. So bleaching action is the conversion of color pigments into colorless thing. Right. That is the bleaching action decolorizes. This property is important. Oxidizing agent bleaching action. That question you will get. Okay, it's a powerful oxidizing agent. We have seen that it shows oxidizing nature. Along with oxidizing nature, it also behaves as reducing agent. Next time you write down reducing agent. It is also a strong reducing agent, strong reducing agent. Because we have silver oxide ag2o reacts with H2O2. It reduces silver into silver metal plus H2O and oxygen evolves. Yeah, once again, I'll go back. Okay. So wherever it shows reducing action, it always releases oxygen gas. Right. When they ask you some questions in a school exam and all. You have to write down the answer all this and you have to support your answer with some examples like any reactions like this. Like, could you tell me what is the oxidation of silver here in this compound oxide. How it is plus four pranav. Yeah, it's plus one correct so minus two, and this is plus one. What is this zero, because we have independent element zero plus one to zero what is this. Oxidation state reduces decreases so it is reducing it is getting reduced. So it's a reducing behavior of it. This reaction is important. Claudine when reacts with H2O2, it converts into HCl and oxygen gas evolves. So in all these reducing behavior, we have oxygen gas comes out. So oxygen is a part of H2O2 only now. So H2O2 will reduce chlorine and oxidize itself. So oxygen will get oxidized. That's what the thing is. Both won't get reduced now. H2O2 oxygen is a part of hydrogen peroxide initially. It oxidizes, sorry, it reduces chlorine and get itself oxidize. Ag2O also silver will get reduced and this minus one converts into minus two and zero. So H2O2 also have the property of showing the disproportionation reaction that was the next point I was about to talk. Okay, it have the tendency to goes under auto oxidation reduction that is disproportionation reaction. So here what is happening that's a different thing. But this one is reducing silver. So it is a reducing agent. Right down next point it is unstable in nature. It is unstable in nature and goes under disproportionation reaction. That is auto oxidation reduction to H2O2 converts into to H2O and O2, zero minus two minus one auto oxidation reduction. And the last reaction for this you write down last property is the acidic nature. And we have discussed this thing in the docs that if you have peroxide in peroxide the oxidation state of oxygen is minus one if you remember that. Oh, oh, oh, so minus one, minus one, plus one, plus one, this is the structure we have what zero I didn't get you. Here it is minus one, here it is minus two and zero. Yeah, so oxygen is minus one I'm talking about oxygen here. So oxygen is getting reduced and oxidized. Correct. In water we won't have it will, you know, decompose into the ionic form. A little bit, not much. We don't have traces of peroxide in water. So acidic nature you see it reacts with alkali solution. It reacts with alkali solution and give corresponding peroxides. Like for example just two example here H2O2 suppose reacts with NaOH it forms corresponding peroxide so Na2O2 and H2O2H2. It reacts with suppose Na2CO3 again it forms Na2O2 plus H2CO3 which decomposes further into H2O and CO2. This is the acidic behavior acidic behavior you can understand it is base this reacts with one compound giving water. So it is base acid acid base reaction clear understood. So we are left with one last thing in this chapter that is the water molecule hardness of water and all we'll discuss we'll discuss this after the break. Correct. So heading you write down water H2O. We'll discuss this after the break. Correct. We'll resume the session at 620. Sorry 630. Take a break now. Yeah I know I'll just put it in the charge. Okay take a break guys.