 next write down by the electrolysis of water electrolysis of water what is electrolysis electrolysis through the electrode right so we'll have one anode and one cathode in this right so write down anode is made up of write on like this for electrolysis of water anode is made up of anode is made up of nickel nickel plated iron rod and say when iron rod nickel plated okay cathode is made up of iron rod so anode what happens oxidation always at cathode reduction always and we use nickel plated iron rod we can also we can also use this also platinum and nickel plated and both we can use other books also we have so we have one more electrode here now this electrode one of the electrode is anode another one is cathode and this is okay this electrode is connected through an external voltage source okay external voltage source this electrode which is connected to the positive end the electrode is anode in electrolysis the electrode which is connected to the positive end is anode and this one is cathode and we use NaOH at what's NaOH solution here or we can also use H2SO4 because pure water is bad conductor of recticity to make it good conductor we mix some amount of NaOH or H2SO4 10 percent NaOH or H2SO4 okay now whatever ions are present here in the solution we have OH- here we have OH- H plus Na plus these three ions are present in this all these negative iron will move towards the positive electrode and positive iron moves towards the negative electrode right okay so here what happens we have only one iron which get oxidized OH- will get oxidized here and we have two ions here H plus and Na plus which has tendency to get reduced at cathode the one which requires lesser electrode potential will get reduced first okay so here what happens at cathode Na plus also has tendency to get reduced but H plus will get reduced here because it requires lesser electrode potential right so reduction of H plus here and oxidation of OH- and anode two reaction takes place and we have two outlet here from this O2 gas comes out and from this hydrogen gas comes out So why will Na go before H2SO4? See Jo, that will reduce first Na plus both compete here for reduction the one which requires lesser energy why is H plus have lesser energy why does it require that for that we will discuss that in electrochemistry electrode potential may hydrogen electrode is assumed to be the reference and the electrode potential of hydrogen electrode is assumed to be 0 if this electrode potential of H plus is more than to that of Na plus then this will get go under reduction if this is more than this will go under reduction and there is one more term that is over potential so over potential we will discuss that but usually what happens the ions which are competing with each other depends upon the electrode potential one will get oxidized or reduced okay so here oxidation of OH- takes place and reduction of H plus takes place the reaction of anode you write down the reaction of anode will have OH- 2 OH- converts into H2O plus half O2 2 OH- converts into H2O plus half O2 and 2 electron goes out this is the reaction at anode oxidation reaction you see the electron is getting released right and that H plus will take this 2 electron 2 H plus plus 2 electron converts into H2O this is the reaction so in this one happens at anode oxygen gas evolves this is important at anode O2 evolves at cathode H2O electrolysis of next write down boss process boss process catalyst used nickel catalyst is nickel temperature around 1270 Kelvin write down write down in this reaction superheated steam 1270 in this reaction superheated steam is passed over is passed over red hot coke carbon solid so the reaction is carbon solid plus the steam H2O converts into CO plus H2O the reaction is the reaction is endothermic okay this we call it as this mixture we call it as water gas this mixture is water gas where carbon monoxide presents as an impurity here right so we have to take this CO out okay so for that what we do write down this is impure hydrogen this is the this is the what we can say impurity this hydrogen is not pure or to pure this to get pure hydrogen here what we do write down impure hydrogen is difficult to remove it's difficult to remove and in order to get pure hydrogen in order to get pure hydrogen carbon monoxide write down like this in order to get pure hydrogen we have to oxidize CO into CO2 carbon monoxide into carbon dioxide the catalyst used for this purpose is ion chromate to oxidize CO into CO2 we use ion chromate that is FeCrO4 ion chromate is another catalyst we use here to oxidize carbon monoxide into carbon dioxide water gas we also call it as syngas or synthesis gas that is also another syngas or synthesis gas all three are same water gas syngas synthesis gas okay so with the help of this FeCrO4 carbon monoxide oxidize into carbon dioxide and that escapes easily into the atmosphere and we get the pure hydrogen this plus H2O in presence of FeCrO4 gives you CO2 plus 2H2O this escapes and we get the pure hydrogen okay thermal cracking also we can use hydrocarbon cracking of hydrocarbon for the preparation of hydrogen you must remember this one is important the catalyst used in boss processes nickel it's not ion chromate ion chromate FeCrO4 we use for the oxidation of CO into CO2 you can do whatever you want okay banana is important because you have the arrangement right so like you see they say so this side hydrogen is getting involved and it's an oxygen order so if you have an arrangement here so that you can store the gas which is for because CO2 is a tendency and that's how you say it can escape into that atmosphere if you want to store CO2 also store the compounds okay okay next slide down compounds of hydrogen right now next compounds of hydrogen compounds of hydrogen the first compound is hydride okay hydrogen forms generally three types of hydrides as I said we can have more dictates okay first type is ionic ionic hydride we also call it as salt like hydrides or we also call it as saline hydrides saline hydrides all these three are same okay the another type is metallic or we also call it as non-stratometric interstitial hydrides again all these three right the last one is molecular hydrides molecular or covalent hydrides covalent hydrides this is three different types of hydrides it forms okay now ionic salt like hydrides are formed by the elements of the periodic table we're going from left to right okay so left is splot group 1 and group 2 right group 1 and group 2 forms ionic hydride example NAH LIH say the two hydrides of this group group 2 that is BEH2 and MDH2 BEH2 and LIH2 is also their partially covalent characteristic but it is not that great right but BEH2 it is covalent this is an exception okay so this is uh BEH2 BEH2 is covalent hydride it is an exception we can also discuss the logic behind this we'll discuss that but it is covalent hydride and the exact answer for this one it is partially covalent and partially ionic okay if you have to choose but in ionic and covalent this one is also covalent right so this one is if this option is given then we'll go with this for magnesium okay if you have to choose between covalent and ionic we'll go with covalent it is not an ion okay why it is covalent because of the small size of beryllium BEH2 plus because of its small size it polarizes the hydride ion right and because of polarization we know Pheasant's rule right polarization leads to the covalent characteristic so the reason behind this is what polarization here and here also because beryllium has the smallest size in that group BEH2 right because of Pheasant's rule polarization this is covalent this is partially covalent partially ionic okay so with these two exceptions all of the elements are considered to form ionic hydrides okay here okay second part metallic is what metallic is d-block elements right so right on here it is mainly formed by and right on mainly formed by d-block elements mainly formed by d-block elements few examples we have VH 0.56 is possible and another one is for VH2 after this you write down these elements does not follow these elements does not follow law of constant composition law of constant composition okay so all these three types these type of hydrides like carbon-oxygen composition if you see can form CO and CO2 both so constant composition law it does not follow same thing you have a different proportion of vanadium and hydrogen at a condition right so that is what we are doing so because it has a different at a different condition it's like composition over the vanadium on hydrogen so this can form this hydride and this hydride is also possible and that's why we say they do not follow the constant law of composition of 0.5 it you need because we need around 0.5 so when the two elements combine so it will have a certain condition for that this ratio is also possible for this combination this is also possible different different types of hydride forms okay like carbon forms carbon monoxide and carbon monoxide if we can change the condition then the the number is to actually be anything anything between 0.562 can be anything it's not because we can all right you can because the lattice structure changes yeah i'm not going to that day when you change the temperature the lattice structure will change why one more question when we approach absolute zero why does water's lattice become a square absolute zero temperature all kind of motion freezes right like there is no vibrational motion there is no translational nothing is there right so what can remain hexagonal why does it become a square it's a hexagon okay yeah when it becomes super cold it suddenly becomes a square so there is only one element that is chromium which forms the style of hydride okay group six to group nine only one element which is present in group six forms which is chromium forms this kind of hydride and hence from group six to group nine is known as hydride gap the question i i examine about what is hydride gap it is observed in from group six to group nine chromium is the only element in this group in this range which forms this hydride part a reason is that only the lattice structure and conditions are see when you when you go left to right okay left to right when you go there are many things we'll have ionization potential changes size changes electrons in the inertial also changes right so that affects the property of the elements how the two elements combined by the exchange of electron sharing or or transfer of electron right so for that what happens all these conditions what i said size number of inertial electrons has a has an effect on this okay and a given condition right so that is why it is not forming for all of the elements only for chromium so six to nine we call it a hydride gap only chromium forms this right right sir six to nine do are there no hydride forms or only no men only chromium forms okay sir but can the others form like six to nine chromium forms hydrides of this type ionic molecule work for all elements does not form any kind of matrix except chromium six to nine third one right on covalent hydrides covalent hydride is for it is mainly obtained by p-block elements right as plot p-block and p-block elements so p-block elements in this also we have three different types of hydrides electron deficient electron precise and the last one is electron rich electron rich these three types of hydrides yeah electron deficient is formed by the elements of groups 13 ph3 al h3 electron deficient this is formed by the elements of group 14 ch4 exactly eight electrons ph3 has six electrons for boron ch4 electron rich is obtained by the elements of group 15 one lone pair group 16 two non pair and group 17 three lone pair h3 h2 and hf