gases in the atmosphere now in this chapter we're going to discuss the air the atmosphere around us and the gasoline present in it and some common reactions or how we can calculate the amount of gases in there the reactions of those gases and other other relative information let's start with the composition of the air before we go with the composition of the air let me explain something that this composition these percentages by volume are for unpolluted and dry air so we consider the air is not polluted with any of the pollutants by pollutant i mean anything that is harmful for the living things and present as a part of the air are harmful for the planet as well we also consider the air to be dry which means we do not include uh water vapors in the air when i talk about water vapors the percentage of water vapors can be different in different areas this is given in this key point air can have anywhere in between zero to four percent water vapor and the percentage of carbon dioxide is though small in the air but is rising steadily because of human activity so talking about that nitrogen is present 71 by 78.1 21 for oxygen 0.9 for argon and co2 is 0.04 percent so approximately speaking if we ignore the smaller ones this is about four-fifths of it and this is about one-fifth of it there are many other gases present in very small percentage in the air specifically noble gases which means helium neon krypton xenon they're also present over there by this we mean these gases right these are the ones i'm talking about okay helium neon krypton and xenon we have very small percentages of these gases so that's the composition of air now we do different experiments in different questions uh regarding the composition of air though this seems very simple and straightforward but these fractions are important keep them in mind because we're going to consider them also this whole table is to be memorized by the student right [Music] so moving on showing that air contains about one-fifth of oxygen we can do that by removing the air or by relying on the very basic principle that oxygen is a reactive gas and can easily react let's go for a practical then it's pretty easy how we can go for it for example practically using copper what we can do is that we can take two gas syringes a bigger one and a smaller one and in between them we have a silica tube packed with copper fillings as copper has a red brown color that's why it's shown in red brown all right so this is red brown colored pure copper okay so what we do is that we originally start with 100 cubic centimeter of air filled in this one so you can see the plunger is exactly at hundred and you see you would see this cat syringe plungers is moved all the way in so there is no air in this one so that's what written over here let's go through it line by line so we would know the steps of this practical the plunger on one of the gas cylinders is pushed all the way in this one and the other one moved out to 100 cubic centimeter so we know that the apparatus has a hundred cubic centimeter of air now we're gonna prove that out of that air one over five is oxygen so silica to be heated strongly using a roaring person flame that means we take a while to heat it up and then we start with the experiment the plunger in the left-hand gas syringe is pushed in this causes the air to pass over to the over the heated copper and this pushes out the plunger on the other side so this is pushed slowly all the way in and this one goes all the way out we keep doing in that sequence we push the left hand side over to the right the right hand side over to the left this is done in sequence this is done many times you can perform the same thing i mean pushing this plunger slowly in so that this one goes out and then push this one in so this one goes out that's one circle and you go can go for four to five loops even more you may go with nine to ten loops you i mean push this one in and then this one and this is one loop and go repeating that a few times now the copper reacts punch and burner is moved along the tube so that it is always heating fresh copper that reacts with oxygen the volume of gas in the syringes falls as the oxygen is consumed we keep pushing the plungers in and out till there is no change in volume so roughly after four to five times maybe afternoon ten times if we are heating it at different points during different times for example for the first three times you can heat it in the center for the next three times you can heat it over here for the next three times and heat it over here so we can make sure that most of the copper reacts with oxygen we keep doing that until these plungers uh move slowly to one fifth of it and remember if 100 is divided by 5 that is 20 so approximately the plunger will go from 100 all the way to 80. and when this volume around 80 becomes constant and there is no change we stop pushing the plungers in and out right let's go with the further calculation now initial volume of air in the system was 100 you will find out a final volume of the air to be anywhere near 80 it can be 79 it can be 78 it can be 80. somewhere around that the more accurate you are the more chances of this number to be exactly around 79 the volume of the air has decreased because the oxygen has reacted with copper in this specific reaction in which it forms copper two oxide and we can work out the data that initially find initial minus final gives us 21 cubic centimeter and the percentage would be 21 over 100 multiplied by 100 that is 21 out of 100 the number remains the same in fraction as well as in percentage so the number was 21 as well as the percentage is 21. that's basic mathematics makes sense can you repeat i mean when we are working with 100 and we get a number and then we find out try to find out the percentage it would be 21 over 100 as we are working with 100 and in case of percentage we are supposed to multiply the whole thing with hundreds just like that being done over here so this cancel out this and the answer is 21 again so i'm trying to say if we are working with 100 the answer remains the same and percentage get the point yes but why did you subtract 79 from 100 because we are supposed to subtract the initial and final volume of air let me explain air contains let's go for the first table again nitrogen four over five and oxygen one over five now as we used copper if only oxygen reacts with copper we will get this kind of reading because only this one reacts so if we started off with 100 and we subtract the reading we had which is 79 will get this volume and by this if 21 over 100 in 200 is equal to 21 so that means this one is around 21 and by the way 1 divided by 5 the answer is close to 0.2 which means the same thing in percentage get the point if we do not subtract these values we would never be able to find out how much oxygen reacted see we started with 100 cubic centimeter out of which 79 remain this 79 is actually nitrogen which does not react with copper because copper plus nitrogen no reaction so that's how we know this 79 cubic centimeter is nitrogen and the rest of it is oxygen and that's how we can calculate the percentage of oxygen get the point yes good good so there are a few things on the sides in terms of key points that we should go with wear eye protection and heat carefully to avoid the cracking of glass syringe with the flame because if the flame touches the glass range it would easily be able to break it take care not to push opposite plunger completely out all right so after 100 if you're gonna keep pressing it this might go out so don't try to push too hard just go with the values and normal pushing sometimes students try to pressure too much and then the plunger goes out of it and sometimes even break the syringes so try doing it in a nice and clean way instead of pushing too hard when doing this experiment we need to make sure that we use enough copper to react with all the oxygen in the air so copper must be in excess there will be some unreacted copper metal at the end if we do not use enough copper the value we will get for the percentage of oxygen would be too low because not all of the oxygen has been removed this is a very important point remember how would we know that some of the copper has reacted and some of it hasn't now this is where the part kicks in the copper is pink brown and the copper oxide is black so by the end of the experiment there should be some pink ground copper left in the system if all of it is black you probably the oxygen value you'll get will not be 21 and would be less if there is some pink ground copper left you'll get the value 21 you'll get an accurate answer which ensures that there was excessive copper and some of it reacted and some of it left unreacted make sense yes good remember the colors the colors are important as for papers and you are supposed to memorize these colors so copper is pink prior to red brown and copper ii is black moving on remember we have put inverted commas around here because we are talking about air from which the oxygen has been removed as most of the air is nitrogen and nitrogen is very unreactive and so if you put a lightest plane into this air it would be extinguished this is the way we can check it this is a very important point all right so if you have just nitrogen left in the air and all of the oxygen has been consumed in this kind of reaction if you put a lighted splint into this air i mean mainly nitrogen gas it would be extinguished this has been a part of past papers remember burning requires oxygen so to keep the splint lighted we need oxygen and in this kind of air if the oxygen has been completely removed the splint will extinguish instantly almost instantly all right okay so if we are clear with this page can we move on yes great so there is another way we can put it up now iron needs oxygen and water to rust we are going to discuss that in a later chapter so we can use a practical by the resting of iron to prove that there is some specific amount of oxygen in the air again we're gonna prove it as close to one over five fraction now iron rusts in damp air using up oxygen as it does so we can use this reaction determine how much oxygen there is in the air now in order to go with this react whole practical we need a conical flask we need some wet iron fillings we need a connecting tube make sure you airtight this conical flask by using a cork fitted into it along with that this connecting tube is connected to a gas syringe the gas syringe is put exactly at 100 or even if we start with some different volume we can always note it up that's fine it doesn't have to be exactly 800 in the start of the experiment we may do it with some other reading but we definitely need to name and note down the reading now we're going to use the apparatus from this figure before we start we need to know the volume of air present in the apparatus we can do this by filling up the conical flask and the connecting tube with water and then transferring the water to a measuring cylinder on the conical flask we mark the position of the bung and only fit with water to that point we will assume that a very small volume occupied by iron flailing is negligible so very small thumb volume compared to the overall ones that's how the iron fillings get wet so the procedure for this experiment is as follows set up the apparatus put wet iron fillings into the conical flask and then record the initial reading on the gas syringe leave the apparatus in place for about a week remember this we are saying on purpose resting is a very slow process it's a slow chemical reaction so it takes almost about a week for it to rust a little until the reading on the gas range stops changing record the final reading we started off with 130 volume of the air in connecting tube was 12 initial reading on the gas range was 92 and the final reading on the gas length was 43 right so the total volume of the air inside the apparatus let's go with that conical flask connecting tube gas syringe the total is 234 okay now the final reading on the gas syringe is 43 the total volume at final rating again conical flask this one is connecting to and this one is the gas syringe in the after case so take it as a before case and take this one as an after case right so this value is 234 this value is 185 subtract them it's 49 decimal centimeter cube now we 49 centimeter cube is the reading after subtraction we started off with 234 and then multiplied by 100 for a percentage and the answer to that would be around 21 percent again right so it's the same way we're going to subtract we're going to divide the subtraction value the answer that we get by the overall value we started off with multiply by 100 to get the percentage of oxygen this is the percentage of oxygen present again it's almost one by fifth of the whole thing makes sense yes okay if it does you would definitely be able to understand the thing we are about to say next sometimes when you do this experiment the answer comes out as less as than a 21 percent there are some possible reasons for it the experiment was not left set up for long enough that's why we said about a week in some areas where there are drier regions hotter countries we might need more than a week might need two so the iron doesn't it did not have enough chance to react with all the oxygen that practiced the answer can easily be less than 21. the answer could be around 18 or 19 maybe 14 or 15 you know you never know or not enough iron was added at the beginning so the iron must be in excess that is there must be enough iron to react with all the oxygen present so just like we were saying back in the case of copper we said the same thing in case of iron we need ample amount of iron to react with oxygen and how you gonna get it any idea how would you know that this amount of iron is emperor [Music] okay let me help you with that in terms of the modes chapter remember we had the most chapter to calculate this out if you have the equation you can always calculate for example back in practical one and i'm not going to scroll a couple of pages i'm just going to write the equation i hope you remember in the previous practical we had this kind of equation for copper do you remember that yes okay so if this was the amount of oxygen and we had roughly 21 of oxygen we had 21 cubic centimeter of oxygen we can always calculate the number of moles for it by that i mean for 21 cubic centimeter that is 0.021 divided by 24 and number of moles would be around something zero point i guess 0 7 i don't know i don't have the calculator in front of me and right now do you have the calculator with you yes why don't you go ahead and help me with it this is the symmetra cube and this one is just a meter cube per mole so we'll get the answer in moles so 0.021 divided by 24. 8.75 8.75 times 10 to the power minus 4. yeah that makes sense 8.75 into 10 raised to bar minus 4. this is the amount of moles so if these are the moles of oxygen that are going to react the double amount will react with copper so it's as there is two with this copper and one with this oxygen so we're gonna multiply two with point seven five into ten raised to power minus four moles what's the answer to this one seven one point seven five no i think 1.75 into 10 is to power minus 3. am i right yes okay so if this is the answer for moles of copper we can simply calculate the mass from for it so 1.75 into 10 raised to the power 3 and the molar mass of uh sorry i mean the relative atomic mass of copper is 64 usually so 64 into this what's the answer to this one zero point one one two zero point zero one one two yeah just one one two right right so this is the grams of copper that we require for this one in order to make sure we have ample amount take any amount bigger than that for example you may go ahead with 0.2 grams of copper which is far more than this one get the point yes so with this kind of calculation we can easily come up with that okay so you may go with 0.2 0.3 0.4 anything more than that if we have uh two to three times or four times more copper we will easily be sure that we have excess of copper to react with oxygen in the similar way i'm going to clear this up can i get it up or do you need a screenshot first you can clear it up all right so if we talk about we're going to talk about practical 2 by the way it can't be we can't be certain about this equation because usually the formula for rust is different we usually show it with x's at this level but let's go and talk about this like this so what we can do that's how it's balanced so what we can do we can always come up with the amount of oxygen as a amount of iron required for this amount of oxygen right so as we have taken 49 cubic centimeter of oxygen in this case so we can always calculate the amount of iron needed in the very similar way we just said for copper make sense yes and i've used this 49 value over here okay so if you're clear with this one let's move on third practical we can use phosphorous now phosphorus is a very reactive on metal now it reacts with oxygen in the air and it forms a phosphorus oxide this oxide is very much soluble in water actually it produces an acid upon dissolving in water uh phosphorus does not react with water directly however the oxide does now we are supposed to fish set up the apparatus as shown in figure 13.4 with the piece of phosphorus on the evaporating basin and then there is a bell jar and we have a trough that is filled with water and actually the evaporating basin is floating in water the initial level of the water is marked on the side of the bell jar with a waterproof pen or a sticker i mean like over here or here okay so a bang the bung is removed from the bell jar this one so and the phosphorus is touched with a hot melt metal wire in order to ignite it the bung is quickly put back into the bell jar this must be real quick if you're quick with this step you your calculations will be accurate or close to accurate if you're not quick with this step you're slow your calculations will change as slow as you are right the more slow you are the more your calculations are going away from uh being better or precise the phosphorus burns the bell jar becomes filled with white smoke which is phosphorus oxide and a level of water rises inside the bell jar the smoke eventually clears as the phosphorous oxide dissolves in water when the level of water inside the bell jar stops rising the final level is marked which in this case you can see can be marked over here and here so we marked it over here and here so you can obviously notice there is a difference to the water level rules so if that makes sense we can always come up how much the water level has changed the belgian is turned upside down filled with water to each mark in turn and the water is poured into a large measuring cylinder it is important that there is still some phosphorus left on the evaporating basin at the end of the experiment and we have used an excessive phosphorus just like we were using excess of copper or excessive iron so that there is more than enough to react with all the oxygen if there was no phosphorus lead then we would probably get a lower value for the percentage of oxygen because not all the oxygen might have been used up that means a wrong experiment we might need to do redo it with a bigger or more excess amount of phosphorus right now the teacher demonstrating needs to wear goggles and a face shield to have the room well ventilated after igniting the phosphorus the bell jar needs to be held down as pressure rises initially after all the fumes have gone evaporating this needs to be sunk using blast rod to prevent any unreacting phosphorus reigniting as phosphorus ignites in a pretty bad way so we need to be safe about it all right that's why we intend for a teacher's demonstration and at this point we don't ask from the students to do this experiment now the combustion of elements in oxygen some elements burn in oxygen we call them combustion reaction elements burn more brightly and rapidly in pure oxygen than in air because air only contains 21 percent of oxygen as we just proved with three different practicals so starting with different reactions burning magnesium magnesium burns in oxygen with an extremely bright white flame it gives a white powdery ash and that is magnesium oxide the white powdered formed is not very soluble in water but a very small amount does dissolve to form an alkaline solution which is magnesium hydroxide clear enough yes so we are going to go with different reactions make sure that you remember all the visual observations for example extremely bright white flame or white ash powder formed or which is not very soluble in water stuff like that has to be memorized by the student next up is burning sulfur sulphur burns in oxygen with a bright blue flame and this blue flame is pretty good to watch it's poisonous colorless sulfur dioxide gas is produced this is the reaction this gas easily dissolves in water to form an acidic solution and the name of acid bond is sulfurous acid the formula for which is h2so3 sulfur dioxide is also known as sulfur 4 oxide remember the 4 is written next to sulfur to show its oxidation state makes sense yes okay so sulfurous acid is h2so3 and sulfuric acid is h2so4 so these are two different acids having two different names in two different formulae make sure you don't confuse them moving on burning hydrogen hydrogen burns with a pale blue flame and oxygen and the product is water if you ignite a mixture of hydrogen and oxygen it would explode this is the basis of squeegee pop test for hydrogen that we're going to perform in upcoming chapter 18. however a very little amount of hydrogen is done for this purpose taken for this purpose and that little amount of hydrogen gives you squeaky pop this is going to be a pretty good experiment for the school lab for the students because students love this experiment every time we come up with experiment they would like to go with the squeaky box the sound is beautiful and they tend to perform the experiment over and over again this comes as a fun experiment in lab um i guess you would be able to do it in your own lab if this routine chrona routine changes so remember we take a very small amount of oxygen for the squeaky pop and if the amount is a little bit higher it would explode this reaction has to be done with care i hope the teacher helps you how to get a small amount for a squeaky enough for a sticky pop moving on there are some oxides that we need to study the oxides are actually compounds of uh different elements with oxygen that can be divided into two categories now we're gonna take oxides these are elements with reacting with oxygen let's take e as an element and we can divide it into two categories else elements are divided into metals and non-metals so we can have a metal oxide like this or maybe a non-metal oxide like this so we're going to study metal oxides and non-metal oxides separately these are the two main bifurcations of oxides makes sense yes okay let's start off with metal oxides metal oxides are actually ionic compounds which contain o2 negative ions metal oxides are usually basic oxides which means they can react with acids to form salts metal oxides are usually insoluble in water those metal oxides that are soluble in water to form alkaline solution containing hydroxide ions they actually react with it to form this one okay let's take an example which is probably already written in the next page no it isn't okay we might need to write an example over there okay so make sure you do for example this is a metal oxide now this one is going to react with water in order to form this see so we're talking about oxidizing or negative or two negative being converted into a hydroxide ion which negative so this is not just dissolving water it's reacting with water and that's what this third point explains make sure you note down the example because this is going to help you with the revision when you're done let me know okay okay so i'm going to clear it up and we're going to move on to the next page where we have non-metal oxides and all metal oxides are covalent compounds remember metal were ionic non-metals are covalent non-metal oxides are acidic oxides which means they're going to react with either alkalis or bases to form salts are they different usually these are water soluble and these are insoluble so actually both of them can react to form salts non-metal oxides are often soluble in water react with it to form acidic solutions that contains hydrogen ions for example so3 can react with water to give us the famous sulfuric acid now this can easily give off hydrogen ions hence acid makes sense yes let's take an example for non-metal oxides we are going to take the example of carbon dioxide carbon is a non-metal carbon dioxide would be a non-metal oxide it's a colorless gas it's most easily made in lab by reaction of dilute hydrochloric acid in calcium carbonate in the form of marble chips right so this reaction produces right here the carbon dioxide we require and it can also be obtained if metal carbonates are heated strongly most carbonates split to give the metal oxide in the carbon dioxide this is an example of thermal decomposition remember thermal means by heat decomposition means to break down our component is it to do or more just like here we the example is of copper to carbonate and we broke it down into copper oxide in carbon dioxide so metal oxide and carbon dioxide another example of calcium carbonate we converted it into metal oxide in carbon dioxide so copper to carbonate is a green powder it gives us a black copper to oxide as we studied previously copper dioxide is black in color this also gives us the colorless gas but here we see some dense white smoke as the gas too much gas is produced in a very little space calcium carbonate doesn't decompose unless it is heated at quite high temperatures this is commercially important reaction because we convert limestone and this one has the name limestone into quick lines so this calcium oxide is quick line this is the reaction for copper to carbonate you should remember the colors of copper to carbonate and copper to oxide copper to carbonate is green carbon dioxide is black most of the time the copper compound colors are memorized by the students so every time we are telling you a copper compound we are along with that telling you its color and you are supposed to memorize it now carbon dioxide and global warming the greenhouse effect energy that comes from the sun is re-emitted as ir radiation remember that energy that comes from the sun comes as ultraviolet rays now from the surface of the earth they are remitted as infrared radiation ir stands for infrared some infrared is absorbed by molecules like carbon dioxide the energy is then transferred to other molecules warming the whole atmosphere that's what makes earth a habitable planet right but but again if it heats up the atmosphere a lot it would become uninhabitable because if the environment is too hot for the living things to persist or to survive it would become uninhabitable this is what we call global warming because the entire atmosphere is being heated up due to the greenhouse effect this entire effect is known as greenhouse effect because the entire earth is acting like a big huge greenhouse make sense yes do you know what that greenhouse is because uh the greenhouse setups are usually thought as a part of biology all right great and you would be understanding what i'm trying to say over there now carbon dioxide is produced when fossil fuels such as coal the solid form oil the liquid form or gas the gaseous form are burnt so carbon reacts with oxygen and produces carbon dioxide petrol or gasoline is a common mixture of different hydrocarbons they also react with oxygen in big amounts to produce good amounts of carbon dioxide it's a hydrocarbon a hydrocarbon is a molecule containing just carbon and hydrogen as you can see in this formula there's only carbon and hydrogen in this formula we'll discuss them in unit 4 organic chemistry well we are taking the reaction over here to give you a point that carbon dioxide is produced by all of these fossil fuels be it the solid coal or the liquid oil or the gaseous portion which we mostly handle in terms of methane so carbon dioxide is a greenhouse gas the greenhouse effect occurs when high energy uv uh visible light from sun passes through the atmosphere and warms up the surface of the earth the surface of earth like any other warm surface radiates it back in the form of infrared radiation this ir is absorbed by molecules such as carbon dioxide and they give out energy in all directions they heat up the atmosphere for approximately last 200 years level of carbon dioxide has been increasing why because we are using more and more fossil fuels look around you we are using fossil fuels for cooking fossil fuels keep our homes form fossil fuels to run our cars run the generators produce electricity we're using almost fossil fuels for every single purpose deep luxury or the daily necessity of life right yes so this has occurred since the industrial revolution and due to the burning of fossil fuels and most importantly deforestation cutting down of trees to create more land for agriculture many people believe that the increase in level of carbon dioxide in the atmosphere may contribute to climate change the exact nature of climate change is very difficult to know but some of the things scientists believe could happen are that the polar ice caps would start melting the ice around arctic or antarctic would start melting in fact it is already happening the sea levels are rising because when the this ice caps are going to melt they're going to give more waters to the sea levels and there could be extreme weather such as floods droughts heat waves tsunamis the list goes on and in this time period i mean in starting with from 2000 to 2020 or 2022 uh we are familiar with quite a lot of tsunamis floods droughts or heat waves so almost most scientists believe that increasing carbon dioxide regards devastating climate change that they had there are others who reject it they claim that the increase in average water temperatures during the 20th century were a part of natural heating and cooling size kills caused by sun and changes to ocean currents they believe the effect of carbon dioxide is very small compared to this but whatever the reasons are we actually have to consider the fact that the entire planet is getting heated up no matter what the reason now looking ahead they are going to go with a few parts but this looking ahead is something that i haven't seen to be a part of past papers however what's important and what we should study are these structures so let's go through those this is the structure of water what is a polar molecule when i use the word polar it means it has slight positive and negative charges on it you would notice that the slight positive charges are shown on top of hydrogen only while the negative charge is shown on top of oxygen now the oxygen atoms attract the electrons in the covalent bond more than the hydrogen atoms that's why we have this delta positive and delta negative small charges represented in them this is not like a complete charge this is like a smaller charge the complete charges that are shown on top of electron are simple negative or proton are simple positive however these charges are shown with a delta negative and a delta positive sign which means it's a little amount of charge not complete we also call it pole that's why we use the word polar molecule in case of carbon dioxide in center you would see a delta positive on carbon and on the sides you would notice the delta negative on both the oxygen atoms the oxygen atoms attract the electrons in the covalent points strongly in the carbon atoms too we say oxygen is more electronegative something that has the capability to attract the electrons strongly than the others but the charges cancel due to the shape a better way of things saying this is the dipoles cancel each other effect because this one tries to pull this away in this direction this one tries to pull this away in this direction and they both apply the same force at the same time just in opposite directions so carbon has a linear structure a symmetrical structure because the forces on the right and the forces on the left are actually cancelling one another or we can say the forces on both ends cancel each other's effects which makes carbon dioxide a more vibrating molecule and it can absorb ir radiation and then it becomes a greenhouse gas the entire reason of discussing this structure is to tell you why it is capable of absorbing energy in the earth's atmosphere and why not oxygen or nitrogen or why don't we call other gases as greenhouse gases so the reason why we call a gas a greenhouse gas is because its structure is built in such a way it's capable of absorbing energy and then re-radiating this energy into different directions that's what carbon dioxide can do oxygen and nitrogen are both non-polar this is the structure of oxygen i hope you remember from the bonding chapter this is the structure of nitrogen again i hope you remember it from the bonding chapter they're non-polar they don't have poles because the amount of charge over here and here will not be different or here or here as they are made up of same atoms they would have equal forces on both ends this one does not have that kind of structure there is positive in the center and negative on the outside so the covalent points are attracted equally there are no small charges on oxygen or nitrogen that's why they are incapable of doing something which carbon dioxide can as a greenhouse gas make sense yes okay uh what i've seen in the past four or five years papers i don't know about uh previously than that i mean if we start talking about 2016 all the way to 2021 i haven't seen a single question out from this a green portion yeah they do discuss carbon dioxide as a greenhouse gas but just out of this portion right so understanding this portion is good memorizing all of it i won't recommend that and this i believe finishes our chapter just let me check on the next page whether we're done with it or not yeah we're done with it any questions so far