 Yeah, can you hear me guys? Yes, I'll be there. OK. So guys, we are going to start a very small chapter. Not much important, as far as the exam thing is concerned. Only one thing is important in this chapter that is this one, the hardness of water, nothing much. So hydrogen and its compounds. So we are going to see the preparation methods of hydrogen and what all compounds it forms and what are the properties of these compounds. So it is a portions of inorganic chemistry and inorganic chemistry, you have to mug it up. You have to memorize it. There's nothing much you have to understand. There are multiple logics you can apply at the same point. But which logic dominates when that you should know? And according to that only, you should find out the answer. So hydrogen is what? Hydrogen is the smallest and lightest element known. Lightest element known. It has its atomic number is 1. Atomic number is 1. Number of electron, number of proton is 1. Number of neutron is 0. Since hydrogen has one electron in its outer most shell, it can do all three types of exchange. It can share electron, it can donate electron, and it can accept as well all the three kinds of exchange possible with hydrogen. That's why hydrogen forms a number of compounds, large number of compounds. It never shows or forms octet, but it forms duplet. Maximum of two electron in the outer most shell it can have, hence we say it forms duplet. Because of three different behavior, sharing of electron, donation of electron, or acceptance of electron, initially there was a confusion, ambiguity, that in which group we should place hydrogen. Should we place with group one or should we go with group 14? That is carbon family, which shows sharing of electron. Carbon family, you see, it has the tendency of sharing of electron, right? CH4, you see? Carbon shares its electron with the four hydrogen. So group 14 elements shows sharing tendency. Group 17 elements, that is halogen family, it has the tendency to acceptance. It wants to accept one electron. Because if you look at this, fluorine, fluorine has nine electron. So 1S2, 2S2, 2P5 configuration we have for fluorine. So it has high tendency to accept one electron, converts into F minus, and octet is complete 2S2, 2P6 configuration is there. That goes with group 17 elements, right? OK, group 13 elements, like I said, carbon has six electron, C6, so 1S2, 2S2, 2P2. So it neither loses for electron, difficult to lose, nor it accepts for electron, that is also not possible. So it shares this four electron in order to make the four bond, the travelency, right? So group 13 elements has sharing tendency, right? If you see the elements of group 1, right? They have tendency to release electron, NA converts into NA plus, and one electron goes out. Since hydrogen has all these three types of possibilities, that's why it was a confusion initially that where we should place hydrogen, should we place this with group 1, or group 13, or group 17. So finally, we went with its electronic configuration, which is 1S1. And since all the elements of group 1, its valence shell configuration is NS1, and hydrogen also has 1S1. Hence, we finally placed hydrogen in first group, OK? So hydrogen is placed in first group, but hydrogen is not an alkali metal, not an alkali metal. It is placed with alkali metal because of its configuration, but it is not considered to be as an alkali metal, because alkali metals are those elements or metals which reacts with water and forms hydroxide, OK? That is the definition of alkali metals. Hydroxide like LIOH, right? NAOH, KOH, all these are alkali metals we have, because it reacts with water and forms hydroxide, OK? And that is not true with hydrogen. Hence, hydrogen is not considered as alkali metals. So because of this properties, it has various similarities with halogen family, with carbon family, and with group 1 elements, finally with respect to its electronic configuration, it is placed in group 1, OK? Now, how do we prepare hydrogen? So right down the next here thing is preparation of hydrogen. Preparation of hydrogen. First one, by the action of water, active metals. Action of water on active metals. See, active metals are generally metals of group 1 and group 2, OK? So you have to keep this in mind. Active metals are generally metals of group 1. That is alkali metal and group 2, right? Alkali metal and alkali metal. So any elements of alkali metal you see, for example, NA plus H2O converts into NAOH plus H2O, 2H2O, 2NA, 2NOH, OK? So metal, hydrolysis, hydroxides, water releases. This reaction is highly rigorous and exothermic, OK? Regress and exothermic. Means heat or energy releases in this reaction, right? Now, in order to slow down the reaction, in order to slow down the reaction, we use amalgams for the reaction. Amalgam for the reaction. What is amalgam? What is amalgam? Amalgam is the alloy of mercury, right? Mercury alloy. So the metal that we are using, instead of pure metal here, we are using amalgam, that is Hg with sodium, in the reaction, OK? Since the reaction is rigorous and exothermic, so high amount of heat releases and there are chances of catching fire, that's why we need to slow down the reaction. And for that purpose, we need to decrease the rate of the reaction. And in order to decrease the rate of the reaction, we are using amalgam instead of pure metal, correct? OK, this actually amalgamated metal that you have, it has lesser surface area. So mercury occupies the surface of metal, decreases the surface area, and hence the reaction rate also decreases, OK? This is the first method we can use for the preparation of hydrogen. Have you done this? If it is deleted in school, let it be, but we have to do it. OK, it's not deleted in J. That's why I won't go in that detail. OK, I'll give you the important things only. OK, Siddish, have you done the preparation? Second method of preparation, you see, by using alkali solution, right on metals like, metals like beryllium, zinc, tin, aluminum, metals like beryllium, zinc, tin, aluminum, reacts with alkali solution, reacts with alkali solution, and evolves hydrogen gas. Reaction is this, BE plus 2 NaOH, it gives Na2BEO2 plus H2. This compound, we call it as sodium beryllate, and hydrogen gas evolves, OK? If you take zinc here, Zn plus 2 NaOH, and if you heat this, it forms Na2ZnO2 plus H2, right? Hydrogen gas evolves, hydrogen gas evolves. This we call it as sodium zincate, Na2ZnO2 sodium zincate. Second method of preparation, third one, actually, by the action of acids, certain metals, right down. Metals with are more electropositive. Metals which are more electropositive than hydrogen displaces hydrogen from dilute acids. So example you see, we can use metals here, zinc, we can use iron, we can use magnesium, et cetera. So for example, Zn plus H2SO4 dilute, it gives ZnSO4 plus H2, Fe plus 2 HCl dilute, gives FeCl2 plus H2. This is the lab method we have, OK? This is the lab method we have. We won't take dilute, sorry, concentrated acid here. We take dilute acid. Next one, by electrolysis of water. Electrolysis of water. It is a commercial preparation method. Commercial preparation method, OK? So in this, let me draw the diagram first. OK, this is the diagram we have. Now in this, we are taking NaOH solution here, right? So this is what? This is 20% NaOH solution, OK? This is asbestos diaphragm. This we use to prevent the mixing of H2 and O2. This one is an electrode. This is also we have electrode. This electrode is connected to the positive end of the battery. And this is the anode we have, OK? Anode. And that anode always oxidation takes place. Oxidation always at anode. This one is cathode. And that cathode always reduction takes place, right? The rod, which is connected to the negative end of the battery of any potential V is called the cathode, which is connected to the positive end is called anode. Anode oxidation, cathode reduction, OK? We have aqueous NaOH solution here, right? So if you look at the ions present in the mixture in the solution, we have ions we have here. We have Na plus ion, right? OH minus ion, H plus ion. Because aqueous NaOH, so water and NaOH both present. So H2O plus NaOH is there. So we have all these three ions present, OK? When the reaction takes place from this end anode, oxidation takes place. Oxygen evolves from this point, this inlet. And from here, H2 comes out. That is how the preparation of H2, a hydrogen, happens in the electrolysis of water, OK? Reaction you must write down. Did you draw the diagram? We have reduction and reduction. We know it is the consumption of electron. So H2O plus 2 electron, it converts into 2OH minus plus H2. At anode, oxidation takes place. So 2OH minus converts into H2O plus half O2 plus 2 electron. This is the reaction at cathode and anode. You can clearly see at anode, oxygen evolve, cathodes hydrogen evolve. Instead of NaOH, we can also use H2SO4 for this purpose. Did you draw the diagram, the previous one? So we have this ion present, right? It is a positive in this positive charge is present here on this electrode, right? So the negative ion which is present here, that is OH minus, which is present here in this solution, as you connect this with the battery, this ion moves towards the positive electrode. And here, oxidation takes place. Reaction I have written, OK? And here, the H2O molecule, it moves towards this side, OK, negatively charged. And reduction happens here, and H2 evolves. Copy it, OK. Next method of preparation we have by Bosch process. The catalyst we use in this process is catalyst is nickel, and temperature we use around 1270 Kelvin. Temperature you don't have to memorize. Catalyst, you must take it off, OK? And this what happens, superheated steam, superheated steam is passed over, passed over red hot coke, passed over red hot coke, means carbon. So the reaction is carbon solid plus H2O in the form of steam, it gives CO, carbon monoxide plus H2O, right? This reaction is endothermic. Energy consumes in this reaction. Energy consumes in this reaction, endothermic. This mixture, CO with water, we call it as water gas. This mixture, important. This is known as water gas. Water gas, we also call it as synthesis gas, or simply sin gas. All are same thing, OK? Since CO is also present over there, so it is an impure gas, hydrogen that we have, right? It's an impure gas. In order to get the pure hydrogen, we need to remove this carbon monoxide, CO, right? So write down next into this. In order to get pure hydrogen, in order to get pure hydrogen, we need to remove carbon monoxide. We need to remove carbon monoxide. And for this, carbon monoxide is oxidized into carbon dioxide. And this carbon monoxide is oxidized into carbon dioxide in presence of FeCRO4. This we call it as ion chromate. In presence of ion chromate, FeCRO4, ion chromate, this works or behaves as a catalyst. So the water gas we have CO plus H2 in presence of water, FeCRO4, it converts into CO2 plus 2H2O. This escapes, and we get pure form of hydrogen. Yeah, so catalyst for this thing, for boss process is nickel. It's not FeCRO4, right? This is the catalyst we use to get the pure form of hydrogen. There are a few methods of preparation of hydrogen we have, apart from this, few more methods are there, like Lane's process and all that. NCRT, you must go through. You will see all those things there, OK? One important point in this chapter we have, I'm just going through the important things. One important point in this chapter we have that is hydrides. OK, what are the different types of hydrides it forms? OK, see, hydrogen combines with various different elements, various different elements, and forms, and forms hydrides. OK, three main types of hydride it forms. It classifies into various categories. OK, so hydrides, we have three main types. We'll do all these one by one. So hydrides, like I said, we have three main types here. The first one is ionic hydrides. Ionic hydrides, we also call it as salt-like hydrides, saline hydrides. OK, ionic salt-like or saline hydrides all three are same. OK, the second type of hydrides we have, that is metallic hydrides, metallic, or we also call it as non-steoichiometric. It is interstitial hydrides, interstitial hydrides. OK, and the third types of hydrides we have, molecular hydrides. We also call it as covalent. Molecular or covalent hydrides. Ionic hydrides are mainly formed by the elements of group 1 and group 2. I'll write down in this only. We can do it in short. These are forms by the elements of group 1 and 2. We have a few exceptions into this. Like BEH2 is an exception. OK, LIH is an exception. OK, MGH2, to some extent, it is also an exception. Sorry, not LIH. BEH2 and MGH2 are the exceptions. So I don't accept BEH2 and MGH2. All hydrides of group 1 and group 2 are ionic hydrides. OK, if you talk about metallic and non-steoichiometric hydrides, these hydrides are formed by d-block elements, elements of d-block. And this is formed by the elements of p-block. Plus BEH2 is also covalent. MGH2 is partially ionic, partially covalent. This general idea you must have. First two blocks forms ionic hydrides, then metallic hydrides, and then covalent hydrides. Correct? This is further classified into three categories. We'll discuss that later. OK, I don't have space here. Few points in all these hydrides you see first heading right down, ionic hydrides. One second. Done? OK, ionic hydrides, like I said, group 1 and group 2 elements forms. So elements of group 1 forms MH-type hydrides. OK, forms MH-type hydrides. For example, we can have LIH, NAH, et cetera. The oxidation state of hydrogen here is minus 1. Have already done this in redox reaction. If you talk about elements of group 2, it forms MH-2 types hydrides. Example, we have CAH2. CAH2, we have SRH2, BEH2, MGH2. It forms this type of hydrides, but these two hydrides are covalent in nature. It's not ionic, it's covalent. And that is because of Faisal's rule. Polarization is small size. Covalent character of BEH2 is more than that of MGH2. These are ionic hydrides we have. These are ionic hydrides. Now, for these hydrides, you see, few properties we have. Thermal stability, write down, thermal stability, first point, thermal stability of these hydrides decreases down the group. So if you see LIH is more stable than NAH, then KH, et cetera, because size increases down the group. Similarly, we have CAH2 more stable than SRH2, then BEH2. Size increases, hence lattice energy decreases, stability decreases. Second property, write down, the density of these hydrides. These hydrides are higher than those of metals from which they are formed. From which they are formed. One very important point here is, accept LIH. Accept LIH, all hydrides can decompose into their parent element, strong heating. So if you heat CAH2, if you heat this around 675 to 775 Kelvin, temperature you don't have to memorize, it converts into carbon solid and hydrogen gas. LIH won't decompose since it has very high heat of formation. High heat of formation, hence difficult to dissociate, because the smallest size in the group. That's why lithium shows abnormal properties. Yeah, one second. Second type of hydride, you see, metal metallic hydrides, non-socio-metric and interstitial hydrides also be called. Mainly formed by elements of deep log, and it's not like all elements forms this kind of hydrides. It forms by the adsorption of hydrogen. Adsorption of hydrogen on the surface of the metal. Properties are what? These are non-socio-metric hydrides. Non-socio-metric hydrides. For example, you see, we have VH vanadium hydride 0.56. We have Iterium YH2, YH3, LAH lanthanum 2.87. These kind of hydrides forms. In this, the density. In this, the density one second. Non-socio-metric hydrides examples is this. Density pair, they have asked questions in the exam. Density of these hydrides, properties only that you have to memorize. These hydrides is lesser than from their parent metal. Is lesser than their parent metal. One very important properties here we have, which they have asked in the exam many times. You see in D block elements, if you consider from group 6, group 7, group 8, group 9. Okay. Group 6, 7, group 8, group 9. Only one element we have which forms this kind of rides. Among these groups, only chromium, only chromium forms metallic hydrides. All other elements of these groups, 6, 7, 8, 9, does not form this hydrides. Right. Does not form this hydrides. And hence, from group 6 to group 9, this range, we call it as hydride gap. Okay. Hydride gap. Must remember this thing. Hydride gap. Third types of hydride you write down. Molecular or covalent hydrides. Molecular or covalent hydrides. Mainly formed by, formed by P block elements. Beryllium magnesium and magnesium belongs to S block, but also forms this hydrides. But forms this hydrides, not also forms this hydrides. It does not form ionic hydrides. Okay. So the general formula that we have here, general formula for this kind of hydrides. For S block, for S block, the formula is MH N type. And for P block, the formula is MH 8 minus N type, where N is the, N is the number of electrons in valence shell. Right. You see for group 2, this belongs to group 2. Right. So it's valence electron is 2. Right. So it is BEH 2, MGH 2. This belongs to N. Right. The valence electron. P block, you can say how many electrons are there accordingly we can write. Okay. Like for you see, for this example for P block, we can write NH3, we can write H2O, we can write or no, BH3, etc. Okay. They are the hydrides of this. These hydrides, that is molecular hydrides, further classified into three categories. Further classified into three categories. Did you write the previous slide? Should I go back? Done. So this is further classified into three categories. Okay. So the first type we have in this, that is electron deficient. Electron deficient means molecule has less than eight electrons. Second type we have electron precise, exactly eight electrons. Electron rich. Okay. More than eight. Electron rich is not more than eight. It's like there are lone pairs present. Donor electrons are there. Means capability of donate electrons. That is electron rich. Okay. Capability of donate electrons. Electron rich. Electron deficient, you know, hydrides are found by the elements of group 30 group 13 elements. For example, BH3 is an electron deficient hydrides. Okay. These are what these are electron acceptors. Since electron deficient. Okay. So electron acceptors. Okay. Act as Lewis acid. Lewis acids are those which has the capability to accept electron. Right. Act as Lewis acid. Once again. Okay. So left to right, you have to go right from the P block group 13. Electron acceptors. Electron deficient hydrides act as a Lewis acid. Lewis acids are those molecules which has the tendency to accept an electron. Okay. Understood. Diaborin is also an example. It's a dimer of it. B2 at six. This is called Diaborin. It is a dimer of BH3 two BH3 molecules combines and forms B2 at six diaborin. Electron precise hydrides are formed by the elements of the next group that is group 13. So the group 14 carbon family. Okay. For example, we have CH4 SIH4. All these are electron precise hydrides. Okay. Right. Nothing much we have important. This electron rich hydrides further classified into three categories again. It is formed by obviously group not three categories. Let it be. You won't say like this. Not required. Rather we say it forms by three groups. 13 14 we have here. Okay. Then this electron rich hydrides we have from group 15 group 16 group 17 all the rest of the groups of P block forms electron rich hydrides electron rich hydrides means what they have you know capacity to donate electron pair capacity to donate EP electron pair. Okay. For example, if you see group 15 group 15 is nitrogen family. Right. Nitrogen family is NH3 and we know on NH3 we have one lone pair. So one lone pair it can donate electron rich hydrides H2O next group 16 you see. Yes. Correct. We can say they behaves as Louis space. They they're no characteristics. It's similar to Louis space. Right. Okay. So this can donate and this can accept group 13 can accept and this can donate and it is in between either donate non accepts electron precise. Another one you see H2O group 16 hydrides two lone pair. And the rest one is HF three lone pair. Right. So group 15 16 and 17 three lone pair behaves as Louis space. These are electron donors. Then yes done. Okay. There are a few compounds of you know hydrogen that is hydrogen peroxide and water molecule to discuss in water molecule will see the know the reason of hardness of water what is hard water what is soft water what is the reason of hardness of water. What is the removal way like how do we remove hard water hardness of the water. Okay. What are the different ways for that. What are different compounds we use for removal of hardness of water. Okay. And only this part is important the hardness of water it's like something like suppose five minutes you have to enter into the room examination hall you have only five minutes and you want to revise quickly some things. So in this chapter this is the one thing that you can go through that is the hardness of water reason of hardness removal property. Okay. Most of the times they ask question from this part only that is the hardness of water and that is the only part which is important. Okay. Next, like I said the compounds of hydrogen the first one is we are going to see hydrogen peroxide so we'll finish this today and water plus hardness will do next class will finish it off. Okay. So how does it peroxide preparation method you write down first one first one from barium peroxide from barium peroxide right on hydrated barium peroxide hydrated barium peroxide peroxide that is B a o two dot eight h two on reaction with with dilute h two s o four on reaction with dilute s two s o four forms forms h two o two hydrogen peroxide reaction is B a o two dot eight h two o plus h two s o four on heating it converts sulfate converts into sulfate plus we have h two o two plus we'll have eight h two one note you write down here and hydrous barium peroxide and hydrous barium peroxide forms forms a protective layer of barium sulfate hydrous barium peroxide forms a protective layer of barium sulfate on its surface hence the reaction is not possible hence the reaction is not possible that is why we are using hydrated barium peroxide for last thing we can also use instead of h two s o four we can also use h three p o four orthophosphoric acid and carbonic acid that is h two co three h two co three is carbonic acid s three p o four is orthophosphoric acid as an asset we can use these two also for the same purpose second method of preparation in this process in this process electrolysis of 50% electrolysis of 50% h two s o four sulphuric acid 50% h two s o four 50% h two s o four is carried out electrolysis of 50% h two s o four is carried out at low temperature using platinum electrode at low temperature using platinum electrode so this h two s o four two molecules of it dissociates as two h plus plus two h s o four minus and this two h s o four minus at anode it gets oxidized into h two s two o eight peroxy disulfuric acid two electrons goes out anode the reaction is this now this h two s two o eight that is peroxy disulfuric acid goes under hydrolysis and it converts into acid and h two peroxide the name of this compound is peroxy disulfuric acid s two s two o eight plus two h two o is two h two s o four plus h two o two ok peroxy disulfuric acid these two are the preparation methods of h two o one last thing is the structure of this h two o two has open book structure open book structure the structure is this hydrogen oxygen oxygen and hydrogen this you consider as the spine of the book o o bond you consider it as the spine of the book and these two bonds are at 97 degree ok nonlinear structure it is it is 97 degree and this one is also 97 degree this bond length is l2 this is also l2 and this is l1 oxygen oxygen bond length is l1 ok oxygen oxygen bond length l1 is more than to that of l2 on this they have asked question in the exam ok why it is more we have lone pair so lone pair lone pair repulsion increases the bond length right so this is structure we call it as open book structure it is nonlinear nonplanar linear and nonplanar structure we have ok understood right so these two properties the bond length name of the structure nonplanar nonlinear you must remember right ok so next class we will see water and hardness of water reason and removal and that is it for this chapter ok I will share one PDF on surface this states of matter you solve that ok did you finish the assignment have you submitted upload it ok I'll close it from my side fine ok thank you so much guys take care bye yeah whatever fine you keep on doing it but whatever you have done by the you know by the schedule date upload it ok and keep on doing it thank you bye