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Lec 7. Solutions and Colligative Properties

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that was the 1st experiment and it did not give the desired outcome the Committee if people are currently getting in which means that you got below 40 that's not but it's not good the highest score was 105 it was possible to do well I wasn't part of the plan but I think quite honestly most of approximately adviser prime players that offices what was the the kind of that you not know what you were doing it you know what you're doing but couldn't execute were you careless did you get mentally flustered all those can issued performance anxiety and rock you are a friend of mine if that's your problem really hard take the exam so that your desk at home 10 minutes on this problem ready go and that if fine don't get this right from the beginning that the become inactive for accuracy get the adrenaline flowing and then practice performing under those conditions that's the way to improve its performance anxiety is the problem if it's lack of understanding that means you have to study hard the only cure that learning is a chemical reaction you have to drive With your force of will or doesn't have you don't get stronger for no reason or by lifting effect on fact by doing anything you can do easily and you don't get smarter or more professional by just looking at end of and never actually working it out it's easy when you see somebody else do it the thinking I can do that if I wanted but you know I got a lot of things to do today and that's not 1 of them soldiers tomorrow that's a problem for some people you're paying a ton of money the company at least from my perspective ,comma you have to make sure that you get every dollar's worth I'm trying to give you good value but I'm only half of the equation the other half is how hard were somebody working extremely hard but honestly she got hand you really need to look at what you're doing and you need to change quickly because you won't have the cost for that kind form finally the fight for the exam form this foreign announced I'm going to pick out the problems that I was particularly worry that the percentage of wrong interest was higher and those problems are going to make an encore appearance on another the study this and make sure but you can do all the props that's the best way OK let's continue our while solutions and collated properly collated properties properties that depend on the number of particles in solution but not on the detail of the kinds of particles who is not so much there are 1st of all it's let's talk about concentrations there 3
common way to express concentration other solutes an assault theoreticians like mole fractions because the irritations don't have backed the measure anything so they don't have the cleaning currently about but they have very nice the areas where the natural concentration is the mole fraction the the fastest man natural thing use drops out of the equations it makes everything so simple they love but an experimentalist doesn't like mole fractions because then you have to to work out the most of the committee meeting the mole fraction is just the number of malls of whatever you've got divided by the total number of small as given the symbol ,comma fancy looking at this I mean I told you we use Greek letters to keep out riff-raff and science Greek letters and limited people in them find out who's not easily intimidated but for example if we take a 10th of a mall of sodium chloride and we have 1 wall of water than the mole fraction of sodium chloride is just . 1 over 1 plus point 1 4 . 0 9 as I say
theoreticians like it but it's not much use them In the letter Canada's want to make up solutions quickly and they wanna make about reproducible and so
that fewer things they have to measure or fiddle around with the better it is you have to weigh out usually have to way what you're going to dissolve in the solution forfeit the gas you have fractured the gas you're putting him that's not such a big deal because those things are usually easily measured and solid stone flocked around it's not too bad but when it comes to the liquid there's an easy job and that is you engineer amount of liquid after the fact and the most common measurement that this similarity with an R and that's the moles of solutes per liter of solutions again chemists like to know how many malls in there because that has to do with how many Adams are in there and that has to do with how many little chemical reactions can occur if I just nominees grams of something and I don't really have a clear idea of what's going on but so we way out the solid and then we just don't and then we make up the solution a mark on a calibrated volumetric flask at the right temperature which is usually 25 Celsius and we're done and that's easy to do because you don't have a way out of the water or put a certain number of it especially if you have put in a certain amount of volume of water it's a nightmare because the water sticks to the container that you used to and their son left
behind so the that's a big problem but to get rid of that we define Larry the malls of selling for leader of solution and we don't want to have to measure the volume of and the glassware companies
will sell you inside like these ,comma things defined the lab and this is probably just the color of but in any case you throw in the solid and you make it up to the mark 1st you had distilled water quickly and swirl it around and that's why it has that shaped so you can mix cities easily I got on the floor and then it narrows here so that you can get good accuracy underscored Mark you don't want to be wife and they're a little like the loss all this is the question of what is happening to today on the news yeah I told you that yes if he tries to make 2 concentrated solution but say you don't know and you try to make and Moeller of something the foreign panels of this stuff and many from the water and a dozen all dissolved then you've got to start over and if you a liquid and another liquid and they form 2 layers that it you are making a solution to just 2 layers like salad dressing after all would be a special case because ethanol is volatile time so when I quarantine and all I have to worry about some of them actually evaporating I go away that type of thing so I have to be a little bit more careful with that if I'm using of all of them but ethanol water will mix and
all proportion but as all show you they don't make an ideal solution technical solution but it's not what's called an ideal which that's a special terms like ideal gap this is the most common thing you're gonna run into and it's it's the easiest to use no question about and then courtesy of some very important experiments it turns out the final
days instead of begin from malaria is little and 4 Molale at and again I told you you don't want to have to measure the volume of solvent but if you don't mind waiting that's all because I can sit there with the volumetric flask and warrants all the while that on balance that I care about the Internet the reason the 2nd half of the and was what the ballot so that's OK and this turns out to be important in certain kinds of experiments that all talk about and so that's also very useful thing to be able to do in analytical chemistry lab and the key we weigh the solvent but we don't have to measure following these collated properties there are a bunch of them boiling point elevation freezing Point depression I was moderate pressure and so forth they all depend on the Mall Laliberty that's what drops out of the the theory that will do and physical constraints let's
practice converting concentrations these numbers are not exact but let's let's just
use and they are tired of being the wife of the more loudly comes up to 5 that's what I call list would strike let's assume that sulfuric acid is 18 . 4 molar and has a density of 1 . 8 2 grams per cubic centimeter what is it small Laliberty 2 that I need to thank what I'm going to do 1st of all I know if I have a leader of solutions I know How many grounds that waste because I know how many grams a cubic centimeter away and I know how many moles of sulfuric acid so if I look at the mall a massive sulfuric acid then I can tell how many grams sulfuric acid is there the rest of it is water because while volumes do not have masses do that's why we liked to calculating matter if you mix to liquids together or solid in liquid the volume will add up in fact and sometimes actually get a little smaller you analyze had because that's something I had can break up the structure of its kind of pushing the thing apart and actually make it shrink but it's very confusing to try to measure things by adding up volume so we never ever do that In chemistry OK let's have a look the 18 . 4 miles of sulfuric acid per liter of solutions those 18 . 4 moles will have a massive 1800 and for . 7 grams then based on the density of 1 . 8 2 and here I'd like to have some more digits the take 1 . 8 2 other thousand cubic centimeters or 1 liter of solutions would have a massive 1820 brands are the 1820 almost all of it is sulfuric acid there's hardly any water this is really really concentrated solution we can do that because sulfuric acid itself a liquid it's a very very viscous liquid itself is not going to solidify its and come out of solution all out of this 1820 1804 . 7 R H 2 SO molecules and that means the other 60 . 3 or what and from allowing I have to figure out how many malls I would have units kilogram of solvent but a kilogram a solvent is a lot more the 15 . 3 gram but the mall Allende is going to be quite a bit higher than
let's have a look the Molale
Attias moles of sulfuric acid per kilogram we had 18 points for moles of sulfuric acid for every 50 . 3 2 and a kilogram we have 18 . 4 moles times the ratio a kilogram of thousand Over 15 . 3 grams and we cancel of units and we have 1200 to moles therefore the solution is 1200 mall and I think that number is in fact quite a bit too hard but I think if you look at the literature you'll find more like 500 well and I think that stand amid falling in the 1 for Moeller and the exact density that I use but in any case it's got a lot higher allergies than malaria and that's always true if you have a concentrated solutions the malaria is much lower than the Molalla on the other hand if you have a guy dialup solutions In plan something would say the water usually they have
close to the same numerical values and so let's convert concentrations again and let's do something but we might find a hospital people have made a very bad
mistakes in hospitals by administering infants 1 Lola have that 1 million Moeller Kabir which led to a loss for the 1st they're supposed value you forget or you don't know what units me the blast this little kid with way a thousand times a of something and even if something the medicine thousand times in my view really not at that idea for anything and you can have their 1st reaction and then if you fail to understand why you're getting an emperor's reactions and deal with it you can have on your hand and you did fighting terror but was taken to wait just don't like this 2 weight per cent sodium fluoride in water and I'm going to use that to its use of patients patients and distressed the puncture vein listing of those that would have been the end of the Transamerica fluid so that they don't own the question is what's the mall and malaria of this solution I wouldn't be safe you on an accident that and I found out that the density of 2 weight per cent sailing is 1 1 0 1 4 3 grams per cubic centimeter the French close to the density of water usually that means it's time to life this the malaria and the mall will be similar let's have a look and let's see what they are go to weight per cent means to GM all sodium chloride in 100 grams of the whole thing with you 100 grams of solution "quotation mark among material and that means that it's got 98 grams of water 2 grams of sodium chloride the 58 . 4 4 GM from all gives this number of malls tiny number more a leader of this solution based on the density it's going to be 1014 . 3 grams of solutions and that's going to contain . 0 0 2 times 1 thousand 415 . 3 because this is the way person for 20 . 2 8 6 grams of sodium chloride I still believe I did here I'm not saying I believe that we can measure you and viability of the whole of the lot but this is an immediate result calculus keeping all the rounded off the land this amount of grams of sodium chloride is . 3 4 7 1 or about . 3
5 smaller usually we would call this 350 nearly the we like the numbers that are bigger than the 1 . our kind of easier for us to understand as long as they are to so it's 350 million Moeller is the concentration malaria of sodium chloride in that 2 weight solution the
rest now to figure out the left Molalla I want to figure out how many grams of water it Emelita of solutions and I've got 20 . 2 8 6 grams of sodium chloride and I know how much the leader of solutions what massive has thousand 40 . 3 so I just subtract them and therefore in that that 994 . 1 0 1 4 brands of water and therefore thousand grams of salt we have this number of moles per 994 . 0 1 4 planted thousands and I should have put the GM in here but it didn't fit across but mentally but the GM with Kansas I never . 3 4 9 2 mold the mall aleady is 350 million Molale attitude but malaria 350 million animal allergies 350 million Molale then close enough a lot is around 150 million loss that's why I think also states that I guess
lecture about vampires but if you transfused the patient with the flu and you will we'll finish the job the government the last leg you're not al-Sayyed where is the on the same they're different concentrations of saving them millions for a different sense of regret the wrong 1 just finished the job on
seawater is 3 . 5 weight per cent salt and that's why here finally seawater because you're thirsty you got you actually get more and more dehydrated and and expired but the urge to drink something lately that fall within the and can be overwhelming I don't know how the you've ever been but I been extremely thirsty and I can tell you that some 30 of water so it's looking pretty good under those conditions you will never ever normal but if you really think that you're going to die time drive is hiding out and turning color and you're getting hot and cold and
stuff like 3 hours ago that was a pretty good so if you get marooned on sale in the ocean sometimes sailors would succumb the urge to stop printing and that kind of like this I want to start thinking something you tend to think that they would that OK let's
talk about this term ideal solutions we had an ideal gas an ideal gas was 1 followed the ideal gas law and real gasses were sorry "quotation mark and if we have a very similar molecule I like to alcohol methanol and ethanol and we make some together economics and all proportions and only a quite a good solution approximated an ideal solution and likewise if we makes toluene and benzene that will also be quiet an ideal solution what does it mean that I will be an ideal solution will 1st it has to make an all for from 1 per cent of it 2 99 per cent of the folks 2 things they always mix entire I never get anything sitting on the bottom I never get to 2nd of all when I mention vapor pressure of each then they follow exactly what the mole fraction of what appeared to like the vapor pressure of each thing in the solutions follows exactly the mole fraction of the stuff in the solution times the vapor pressure of the purely financial vapor pressure pure water something the 400 people and I have an ideal solution and the water has a mole fraction . 9 and the base of the water will be 360 for right on and it'll fall if it's pointed to the 320 and so forth all the way down this 0 and this proportionality between the mole fractions and the vapor pressure His called rounds law it and rather slowly evolving components all the chemicals and solutions follow Roberts of solution is called idea that doesn't happen that often but does does happen From time to time if you pour something a solvent in the temperature changes you need to get colder or hotter Nowhere is going to be an ideal solution way off but that 1 with the poor some man and gets really
hot a lot going on their interactive and so they are going to follow routs law Of course if you pour in to beakers and infect the same thing that's an ideal solution faulted perfectly and they don't really exist but real solutions or sometimes pretty close sometimes they're far off but sometimes they can
be pretty close but let's let's have a look at them these are ideal solutions in terms of the matter but then we use for the mole fractions the pressure of the solution the vapor pressure and this is at a given temperature it is equal to just the mole fraction of whatever the 1st thing in the times whatever the vapor pressure at that you're thing things have different vapor collection and then the mole fraction of a 2nd 1 finds the vapor pressure of the 2nd and if I only have to think then the mole fraction stepped out of the 1 so I can substitute for the mole fraction of a 2nd 1 1 mile from all over the 1st one in a fiery arrange that I see that the vapor pressure of the solution if this is pressure of 1 of them was the mole fraction of the other times the difference and that I like that because I understand that this this is how I want staring between 0 and 1 which it does because small fractions and I can make a plot by stock I want equals 0 0 and the vapor pressure of the other stuff because 100 per cent the other stuff and the increase the amount of the percentage of come on the vapor pressure finally won it's 1 the vapor pressure is the 1 of the purest starts and this is a straight line and therefore provide lot and I look at the vapor pressure and it's always a straight line like that but I know it's following rolled slot
if standards deviating from routs slot and that's just the same as with gasses when we keep doubling the pressure the volume can be passed all the way down to the ball you can go to 0 so it starts per
cent thing here already well let's let's have a look at the solvent if you've got a ,comma and hardly any selling them the solvent usually follows growth law that's the normal and there's a lot the solid doesn't even have much of his other John DNA is probably going to be pretty close to the fearful and there's less of it and so it's going to have less of a vapor pressure of itself and that's because when you have hardly any of the soul you most of the solvent molecules are just seeing themselves if I 1 like Romola of something and I'm there volume on the way I look around I can't even see the sole the way over there and surrounded by this might seem all but it's also inside the case the same find illegal article on the front of the goal of the goal but that's all you know what's around the following is have added to the black sheep in the herd of white cheese she's looking around and saying Hey this environment is totally different than if all these molecules with all you know oftentimes that's all you doesn't follow Brown's law even remotely so I said that here the solutes whatever the minor component is you have to be careful because if you have to liquidate the heart of the site is insolvent and solid but if it's dilute with the Dailey once the sole you even if it's another liquid at the convention it won't follow rattles but it does follow along the problem is the line is different instead of having a vapor pressure the guy you want instead of being proportional to to it's mole fraction which is time times the vapor pressure of the pure solely it increases linearly but it's not the spelling of pressure it's this value K 2 2 which has the units of pressure because mole fractions there is no use at all but the value of this pressure can be bigger for smaller and sometimes by a lot compared to this and that's just because the all you may not be well the solving the problem all you and so it is all but the solid otherwise solvent and want you to get out of here president Bush up with a little bit higher costs and they were also lower than the value of the case file for
the could the the solid love thought it says that under no circumstances lead I'm so tired of the fall here thank goodness from here stay down here Maine interact with them and then the vapor pressure is lower then what you would have predicted by an ideal solution and then the value of K 2 is against France here but it's a lower pressure then the vapor pressure of the
pure solitude and both both cases occur case it is given a name it's called Henry's constants Is this a lot even for a minor component but the pressure changes to yearly with mole fractions but just with the wrong slow is called Henry's Law and went to molecules that are vastly different 1 of them the right to people on the other hand things like that 1 will have a lot the breezy stuff and the other 1 doesn't then that's all you will tend to follow Henry's Law but not dials and as I just said earlier K 2 the larger or smaller depending whether the solutes hates and loves to solve gasses follow Henry's law when it is all liquid for example C O 2 dissolves in water we can make carbonated water and of course when you open so that under pressure and those who this from the existing arsenals sneak out Canadian dissolved 2 which gives you the bubbles with people like you can make your own luck with C O 2 and save a ton of money but more than point this kind calculation is ever so important if you start arguing about how much C O 2 it's going to dissolve in the office the only is a lot of water people were going and a lot of millions of tons of steel you might say Well maybe we can get out of the Jennifer Lopez sealed the result in the ocean and some of well but if you want to figure out how much you have noted that the ocean yet another Henry's law constant facility with Bryna yet another partial pressure seal in the atmosphere you have to know how much C O 2 party dissolved in the ocean because it is up to the top already know more than go in and things like that and in fact we will dissolve more C O 2 in the ocean most likely and that's already been picked up because C O 2 makes the the water solutions acidic we get carbonic acid and in cases where the ocean becomes a the calcium carbonate carbonate structures that many kinds of shells and coral reefs used to build up the structure this all and when that dissolves all the small guys who were hiding out there are out in the open they're gone and then after they're gone the big was around there's nothing that and then there and you can get a fraction the population when they 1st came to fish called on the East Coast and the Atlanta was selling cars in the ocean the latest said many times you could never possibly you just put in in there and just thousands of the discovery and that's what they hear and now there's not that wasn't an infinite supply it was quite fine lots of our food comes from the old so we don't want 1 way or another we don't want really th ocean that some new value and tried that experiment on a global scale and then find out we don't get the result we want which would be far less food production the file that makes made you may think well there will not be so
bad for global warming it could be very bad for global and if you look at where people go fishing now the fishing in the South Pole they're pulling out all kinds of fish that you would never be before and they grind them up column of rare photographs or something they
serve amounted to 6 and the announced that he knows the size of 2 so it may be that there won't be any fish at all as is the case for some kind of the and this year I have known water cannons while images of the here is the mole fraction of ethanol year when the mole fraction of ethanol is 0 it's all water as I increase the mole fraction of ethanol vapor pressure about ethanol all goes on a straight line this is pretty straight but the slow is not this is the vapor pressure of pure ethanol the slope is fine In other words the water pushing out the ethanol more it were just home and that's why it's somebody's dream demand because the alcohol and so on Brown on a much higher level then you would expect and the human nose and pick them up immediately especially apparent they have if you look at water In pure ethanol all it's the same thing here and also the water yet that go on we're happy here we don't want you fluttering around we got our interactions here with this hydrophobic medical group get out until the waters when it's in almost pure ethanol follows a lot but the apparent vapor pressure this is the Henry's constant called kW the Henry's constant is the slow near here and its way higher than the pressure of pure water which is on this on the other hand when we look at the pressure of water when it's almost pure water the mole fraction of ethanol 0 it follows from law it's linear up 2 pretty good concentration and it goes right down 0 it's a following that line and likewise was when it's pure ethanol it follows this line here goes down here and it has the right here if a solution were ideal we could add up these lines and we get this long and this is routs law if ethanol water followed growth slowed exactly that beyond that but it shows a fight amount of total vapor pressure they dislike each other until we get that funny curves and that's the signature of non ideal solution this solution is not very non ideal is kind of a good textbook amount examples and mix them in any amount but it starts deviations from the ideal location now we can use this because and all has a high vapor pressure than water so if we take a mixture of ethanol water and we need it the vapor is going to have more ethanol and the water and start this a long time ago so they this stuff is therefore a matter that has to face awful and they would facilitate and they were state distilled spirits which were much much stronger than here and very happy for and they come out with some of the leaders of the the worst of the member states let's face moonshine from Tennessee or hand sanitizer or whatever the latest trend might be but that is if you wanna look desperate the because distilled and distilling hand-sanitisers and that'll do it but that's what they do is they take that distilled liquor and they put it in some there and they just let it it sit around on and yet very slow chemical reactions and all that stuff that goes away and you also leave
a very aromatic compounds of usually sharing them because some of the cherry flavor that turns a golden color and light villages and small amount but since it takes 20 years to do that started because of the planned 20 years that what
the mangled you just make some and then if it turns out really good it becomes very expensive because everybody wants it and there is no more the demand started we can separated but by fractional distillation these components and that the the ones with the highest vapor pressure will come offer and when they're distilling making distilled spirits there about the monitor there and they don't let the temperature goes above a certain level because if you do then you start boiling over all these awful thing he is a loyal another thing we should give you a whopping headache because there much much more toxic than capital but if you're if you're just moonshine and you probably don't bother with thermometer and you get what you get and if we keep feeding it what will happen this the temperature in the liquid will will keep rising and will get less and less volatile things off with a mixture of a thousand things we can try to separate them by distilling the referred to make a temperature low and we collect something called a fraction we collect 5 per cent and then the temperature goes higher otherwise nothing else comes out so heated up more we get the next fractured and so forth mass called fractional distillation occasionally to things come off together and if that happens you've got something called an ACH but that doesn't change compositions and that's how the nature of they add something to the ethanol so that if you tried distill the they have
long with and Sunday managers usually poised gasoline or something small amounts and then you don't have to face the fact that the other day on that because you
can't drink with Listerine put in the time of the final on political on you can drink very unpleasant in the petroleum industry they do do their thing on a massive scale these columns they have occupied gigantic and the amount of energy that they used do the fractional distillation is just absolutely said "quotation mark incomes of crude oil and million barrels a day all of it oil by somebody that is a lot of energy is going that we eat that stuff and we get various fractions and here we get diesel oil here we get kerosene and jet fuel here we get gasoline here we get snapped the that's for the fine chemical industry and then at the top we get gasses which they cannot not to like because they have not like handled gasses and will be guests of the government this wearing off "quotation mark not about money have the which is astounding but it's been true for along the Gulf Montana North Dakota now where the drilling drilling drilling going Holly Wells it is wearing off that is the point is that doing nothing going up into the sky and a fair amount of C O 2 and then you get some some real bad actors down here that are really down here on this basis he used for ships the so-called bunker fuel and these really take once asphalt those who like the the human and and its strong black said that's what used to play a role the brittle but for every barrel of oil you boil up the whole I really do that with another girl of oil or with this ghastly knew about or whatever where these days you might use natural gas but still all that producing a
lot of C O 2 and then after you take the oil only fractionally distillate and do all this stuff remember all of it too on the vast majority
so the CEO to just goes out of OK now if we add a non-volatile Mike supra or sodium chloride by non-volatile I mean that temperature it's vapor pressure is so low that you can measure then we lower the vapor pressure of the water board the other solvent according to routs law and the lower vapor pressure all the solutions the other thing is contributes no press but when I put it in my lower all fractional solving low solvent has lower vapor from what that means is that the brain the vapor pressure up 1 atmosphere so I've got to go to a higher temperatures because of where it was 1 atmosphere when I wrote this solemn it's now lower and then needed for oil at a higher temperature and that's called boiling point elevation if I add salt water or sugar to water and I had quite a bit it's going to boil at a higher temperature and just pure water the boiling point is elevated it's always elegant if that's
all is non-volatile Bob the kind of solutes doesn't matter much just has
to do with lowering the temperature will see that we can measure the molar mass this way by just changing the boiling point if if we had us all you want to go for sodium chloride to us all like water and this these guys and sodium chloride cannot dissolve in nite that seems like a kind of funny thing to say because these molecules dissolve in water water disorders is liquid natives roll around but when water starts forming Christian I and locked in together the the costing this is growth of all out into the solution what together and I CDs from salt water is still pure therefore if you freeze ocean waters flowing you can get fresh water From the icebergs are all fresh water they could be on waterfront slowly but there's it's all in the eyes of the assault on the surface so far that's not commercially viable option because the problem is watching all this fall all told UGT and hassling them With that but it's theoretically interesting and into somebody who works on it could be used for it's a lot easier to freeze water energy wise if you're call plates senators to boil water and then desalinated by boiling all the water if you wanna energy-intensive things get a couple of cubic miles of sea water and boilers all of this and so you boil it all over and you've got nothing left that's all it's going to take time To do that and those the lower vapor pressure of the solution because I fewer the at the same paper prayer normally you don't think so vapor pressure applied to water quality but consider this way let us physically separated the solution of fall any ice cubes that floating away from and to here "quotation mark separate under an evacuation Belgium their separate anyway 1 and because the ice Europe let's do this way the ISS says a certain vapor pressure if the will of the vapor pressure pure water right 0 that's flight 0 0 the ice has melted here over the water water doesn't read disappear over the eyes the solution now has a lower rate of that means that the price
actually putting up more water molecules in a solution and that means that the eyes has going over here for me it's got along on the so it's going to be lower then it was just the pure solutions so it's going to
reduce that point in the postseason .period depression I have it worked well I don't know you have see what can I do and you may have but it's gene after appears to be a phone the health and lives and get and if we say that the free energy is equal to the NFL the minus the temperature climbed the that if we plot G versus the annotation don't depend too much on temperature which they often dull then but plot she versus the should be a straight line with slope of minus X yes use the entropy that's the lowest for a solid the flow with the
least negative for us all is higher for a late with the slope is more negative assets very hyper down the
slope is extremely negative well I suppose I thought on this slope for these 3 phases and have a look at what happened well here it is the system rolled downhill dislike of all at very cold temperatures solid as I speeded up the gets function of the solid goes down down down down down down and because the gets function of solid is lower than the liquid gas itself because it already fell down at this level but when it reaches this point here it's going to now because now the solids going this way and that materials had I can lower respond much faster by turning into a liquid which is until and that it intersects the gas and then after that a lot down I go again and these 2 points or 1 of freezes and 1 the following the now I have a non-volatile solutes it doesn't change the gas and it
doesn't have a dozen dissolving the solid it doesn't change the solid but it does lower the geopolitical and because the deal related to the pressure however I hold pressure was energy per unit
volume that has something to do with how much Kluivert has and it has last month when it's a solution and so what happens then there's the liquid moves down for simplicity I kept the same law the solid doesn't change because these solutes doesn't dissolve in solve if the solid moved down by the same amount there would be any change they will be here again and the gas doesn't change because you doesn't go into the gap it's non-volatile what we see that is now the solid to liquid it hits this red line and says Wow I'm going to turn into a liquid but it doesn't hit this black line and until fire so there's a lower freezing point and it's usually better because these are less of a slow and and a higher boiling point but it's only a little higher and therefore usually the 1 used this collective property focus on the freezing point you don't like what your molecules in boiling salted because your molecule may react may fall far
or something that happened but usually if you're putting it in the freezer it's easier to see and you can measure the freezing point by cooling it and that's the 1 suddenly let alone off and yet they're quite accurately and then you can sell
the freezing point was was lowered by by a certain amount now we can see this effect of the law vapor pressure of a solution In this practice problems let's consider this up Little are there's nothing in it it's that Delaware and we have a solution that's 10 million Moeller sodium chloride here now we have a solution that's pure water here and we have parents constant Thomas S. important because we made that supplies and energy prevented this is not used to it the question is what we see and I want to tell you that yes the exactly like all pure water will magically and up over here and if it would happen quickly this will be a great the began to fall but unfortunately it happens quite quite slowly
because we have to wait for the Don water molecules that come up here and fiddle around them over here but the pressure pushing up here is always slightly less then the pressure pushing up here so I'm putting on something you're putting me in this position and I'm working harder you go backwards and so all the water ends up over here you can and you end up then with
. 0 5 molar water in the other speaker and when you can see I tried to draw something here were on this side there's an occasional guide here and what it means is there's less guys coming up off the surface maybe this guide tracks them at the last minute to stop global I'll change my ways the flight people there
waiting for us to light and then
these guys are giving more because there's nobody here is saying that it's over time more comes out of the right and ends up on the left over there and so here's what we get I've never tried the experiment that testicular problems is at least
35 years old because it was on a path that will slide that'll this this is an oldie but goodie but I've never tried the experiment have
always wanted to try and just yet to beakers and then sit there and then also see how long but I never had have the time to OK the change in boiling point a freezing .period depends on the kind of salt and the concentration of the solutes in Molale but it doesn't depend on the kind of solutes at least not so we write this equation could change in boiling point it is equal to this factor I times that boiling point like what the tangles of boiling point elevation Const hence the Molale and is is a factor that means if you fat sodium chloride make to particles instead the 1 both for sodium chloride I do because you get twice as many particles and
it has to do With the number of particles In the event the correct name for it is the duty of stopping constant and after you say that a few times you'll see why they changed the name to the boiling point elevated constant name without clear signs and a factor
5 takes into account how many moles of particles the solely makes it's not not the same for everyone for every kind of material obviously freezing Point depression is the same thing it depends on the kind of solvent and the total number of salt so particles we write the same kind of equations have exactly the same In this constant K only depends on us all when you look another case for boiling or freezing was boiling mostly that's all and so that's all it depends on listed for that and the constant chaos is called the price stop constant never heard of Prieto preservation you get a fatal disease and some guy offers the freeze your liquid nitrogen from the gonna warmly backed up when the disease is here that will work with them on it this year and in fact a guy Arizona we're doing this in his garage he had only 6 frozen and their relatives to come by and check out the Giants the people of liquid nitrogen and 1 1 time he ran well on liquid nitrogen in the delivery is going God what am I going to do what might have been and so just let of the guys on and when the soldiers were there and with the moral equivalent of late nite you really get their water from the other guys I went to court but some of the relatives of the frozen man and so was costing too much to the meeting the old guy liquid judge and you declared him dead legally dead which suggested he said Look needs all the legal requirements I'm a lawyer the guys there so they turn them off
so that it's not a good option the freeze yourself unless you can somehow control what's going to happen after which pretty much you cannot OK for sodium chloride ions
to pursue pro-Zionist 1 and so forth calcium nitrate we get 3 ions that all solves & Associates I would be 3 pretty simple freezing point pretty easy to measure and if we can measure the freezing point depression we can tell what the molar massive appear material of we can find some of the and measure the change in freezing point which is dead easy we can figure out what it is and so let's go to a crime scene while not much of a crime forensic chemist is given a white powder half a gram of that results in a grams
of benzene the freezing point at 3 . 9 degrees Celsius could the power of the cold that's the question
OK a lot of things reflect but settlement you can kind of see why cocaine might solvent benzene because they both dancing by structure here and then cocaine has this very interesting structures but the plan makes usually plants vacancies ,comma hound could not the light the plan many colleagues and I think that the Europe plight you can and he thought the crawling all over you and the growing independence you know you're going to survive you have to use chemical warfare eucalyptus stocks during the eucalyptus leaves that have earned my mouth well turned the insects do many things start reading plan the goal line and so you have to do in a war because otherwise the completely dozens or you can result in the loss of by hand thank you all because the relentless uniting called to rest and so it usually means the but that has an environmental impact but presumably this is then made to keep all some maybe there instead of burning the amount would you collect all the features some of the coca leaf and it "quotation mark violence while trying to do here of the anymore and the last wives who knows there are a lot of different for a lot of different strategies plants you but we look up to Mohler massive of this molecule it's 303 . 3 5 3 grams from or and if we look up the freezing
point of benzene yet 5 . 5 degrees C a little bit higher than water and the cries
stop constant is 5 . 1 2 degrees C Her mole out and how do units have to work out but let's have a look and whether it can work yeah the however were 100 per cent cocaine which is the real problem then the freezing point should the crisis stopping constant time the . 5 France convertibles and then divide by 2 . 0 8 kilograms which is a gram and the freezing point depression should be 1 . 5 5 degrees C the observe freezing Point depression is 1 soared 1 . 0 5 the observer freezing Point addresses 1 . 6 a "quotation mark FAA conclusion is it's impossible to that on the 1st hole but sadly hardly anything is going to be 100 per cent of the the most valuable we believe some of the things that matter and you don't know that it's the other things are lowering the boiling at the start of the freezing point by a different amount In fact what you have to do with the sample 1st separated using chromatography or other means until we get things that you see here are pure you can just take a tiny spot the material you can put it on a celebrity and converts solid solid percolates through and if it's Ontario 1 spot move if it was 1 variable you get different sort of Scotland ,comma about you only need a tiny amount see that it's not here yet "quotation mark I want to do because frenzied freeing 5 . 5 and 1 the forensic scientists found it when they put stuffing and frozen 3 . 9 and that's what
wanted no the so the last thing is it is happy be that more men on the notice on the wall you don't know it's not so
much OK but it's not accurate you try some let's let's do 1 more more thing now and then will will quit by the way it is never do it this way if you of a crime and they don't think they have mass spectrometry and they'll tell you you the Olympic testing when they they find 1 another molecule of testosterone and that's that's really interesting chemistry that sort of cloak-and-dagger find out is chief the short answer is everybody's here concerns it is Simon Carr OK if we have a set permeable membrane and we can let through some molecules like water while excluding other ones like charged ions you might think how do you do that but in fact that's what ourselves all the time they letter through potassium in the interior of the salt sodium stays in me last year was so there are membranes that do that what we have an artificial membrane like that the G value is lower for water With some solely because we saw its vapor pressure law therefore we a solution behind a member and put your water on the other side than the pressure in the and the water-repellent
Russian and swell stuff the news considers effect sometimes people who eat too much salt look very healthy for a long time and the kidneys work over time tactic of all that stuff Back to normal none other than the something that worried start with the soul it's not a good idea to steer clear of it and you get just the the right amount just like smoking and you don't need to worry about
Chemische Reaktion
Feuer
Methyliodid
Raki
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Puder
Lammfleisch
Gefriergerät
Kalium
Fülle <Speise>
Symptomatologie
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Ethanol
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Gap junction
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Sieden
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Bitumen
Lösung
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Weibliche Tote
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Genexpression
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Gen
Flüssiger Stickstoff
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Cocain
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Gasphase
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Sammler <Technik>
Nanopartikel
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Coca
Phasengleichgewicht
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Chemische Eigenschaft
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Querprofil
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Bleifreies Benzin
Stoffmengenanteil
Methanol
Chemischer Prozess
Molekül

Metadaten

Formale Metadaten

Titel Lec 7. Solutions and Colligative Properties
Serientitel Chemistry 1B: General Chemistry
Teil 07
Anzahl der Teile 18
Autor Shaka, A.J.
Lizenz CC-Namensnennung - Weitergabe unter gleichen Bedingungen 3.0 Unported:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen und nicht-kommerziellen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen und das Werk bzw. diesen Inhalt auch in veränderter Form nur unter den Bedingungen dieser Lizenz weitergeben.
DOI 10.5446/19469
Herausgeber University of California Irvine (UCI)
Erscheinungsjahr 2012
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Chemie
Abstract UCI Chem 1B General Chemistry (Spring 2012) Lec 07. General Chemistry -- Solutions and Colligative Properties -- Instructor: A.J. Shaka. Ph.D. Description: UCI Chem 1B is the second quarter of General Chemistry and covers the following topics: properties of gases, liquids, solids; changes of state; properties of solutions; stoichiometry; thermochemistry; and thermodynamics.

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