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Lecture 20. Dalton's Law of Partial Pressures


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Monday's sultanate where group much of the right to and that the money some men it against me by the we're going to start acting like a little bit more Nolan's powerful pressures I think really will spend most of the day on on the I'm doing the various versions of this city in the various examples of becoming a little bit while we may it into its fusion of I'm hoping finish up the gas falls on next Monday come and many of us spend Wednesday and Friday on review for you guys I think during the elections and the mask but it really doesn't matter if we can make it through not prominent in another 100 per cent sure we will learn so without all of the deal will be going so revealed in the last 5 minutes last time so remember powerful pressure the way that this works With this works and that you can't take the pressure is on each individual so let's say you have a mixture of Korea for Darfur you can take the pressure of each 1 of them and then add them together and the mutual passion so when we did the ceremony in equation that were in power besides having some conclusions so this is a renowned in just pressure each gas leaks it with powerful I share of the total sold used a fact that we know all that pressure is equal to an hour to reveal a ideal gas we can take and we can solve the pressure for each individual and wooden Adam altogether and we know that if we have a container with a mixture of and the temperature in the volume are going to be the same so we cannot and we can pull that out we can factor in the mold out and then we can get this result is really says that you have all the malls and you can add that in the new year total pressure your moles of all your dad can right into your ideal gas was well insult brutal pressure that led to the ways of doing now there is a very important concept here is that we need to talk about and that's called them all factions so this tax is actually the Greek letters Chi said recently that and this is that if you have the in and all this really is a fraction just like any other factories right it's whatever you're talking about over top of the total so if you want to know the mole fraction in you could take them all the time a new but our problem also called into no differently than saying that those per cent hailing the mole per cent and I accept that you don't have the time 100 per cent that is just the decimal point the factions so that's what we'll factions now what this says is a kind of taking this concept combined with this 1 and says Well we can take that kind we can take them all fractured apart over pulled in we can just times that by the total profit this isn't any different than the sort of how you work with % your entire life right if you want to know what per cent something as of the total you take a fraction in you multiply it by the pool that's so this is your total pressures of I tell you that something has a total pressure finally serious but the mole per cent of the mole fraction of it is only going to take .period to in times of 5 but that don't let this seemed like a new weekly this just this is just using % like you've always use them except what's the 1st thing you do it by the US 75 per cent of something he into after while that all this is it's just the from of the power over half of all so that all more fractures it's like a per except now cents I'm not sure why they go through the year special aspect of meaning it differently calling filed out but you don't time so don't and as the new chief justice kind of a different way meaning in other so far for a partial pressures of actual numbers investors concerned over the quick picture invite and I have this mixture of molecules so I have some purples and tangerines and awkward design and and simply invite you that this has a pressure time for the matter with IC tags in we wanna know the partial pressure pressures staff where we don't have minimal olfaction right so let's start with the purple ones so 1st of all let's figure out how many and what the total number of molecules are total mall Molitor Sir John R. molecules discount 1 2 3 4 5 6 7 8 9 now if 1 or more a fraction of the purple ones what we did was coming for points in a half and I apologize for the color people statistics say there's at least a few you in high do apologize 1 2 3 4 I want that and out answers 4 out of 10 right CIA mole fraction is for time so what would be a mole fraction the big ones when it 600 103 the 3 Maryland that the died from a brain were treating all of these molecules all of these items and all these gasses as just like they're just Europe of all the all the exact same they have no volume they have no interaction have not been just ideal gasses so Soderling matter said users diatonic and users so disoriented now someone other than the pressure of the purple ones quiet 10 so just for so and you can also you can do that with each 1 so the blue just the 1 out of 10 that would be a fraction of point 1 the greens of the 210 . 2 so all factions account a it's how many malls is something you have in this case ,comma Adams works the same way over half of the so now if we were to go through and say Wall 1 of the total pressure of the boxes 30 units than what would it be so that changes things a little bit right but not too much so I mean at the foot of the documents being for this so we can write so let's just do this for a couple of months so we talked about the pink inoperable ones and we talked about kind so it's rated I would suggest is suing the surrenders legislated on the worksheet so we ever think we have a purple 1 as -dash each 1 so you're looking at a
picture and for the team we had said well there's 3 out of 10 In for the purple we had said for Texas is evidence the RCD candidate the green and the blue at home to Nice and will want of the whole world pressure is the 30 whatever because they're talking of molecules are not rules are kind of hard to use normal units so were in a column 13 18 what is going to be our pressure or partial pressure had we figure this out well it's just 2 per cent rate just treating us like a person so
if we wanna know are partial pressure of each 1 we take our mole fraction we multiplied by the total together answer if we took purple we were do for In times of by 30 theater and it doesn't matter that I know I drew 1 answer those kind your ideal gasses a helium neon whatever because that's just monotonic nearly died from his take a mole fraction multiplied by the total and you're done that's a part really nice and he's like kind easy us compared to a that if all of this was
I guess Sister Mary Anderson examples sold best friend is really just examples it's kind of a common theme for the majority of this sort lecture so we have addressed you constantly natural gas tank right in the natural gas can be a whole variety of gasses not just 1 1 thing In making the percentages of each 1 and I say Well what's the partial pressure each 1 given that the total pressure is 1 .
2 so let's break each 1 up for this seat for c 2 age sex In 6 3 8 need to the other partial pressures each 1 so however in India well this time to be a more factory what would idea precise so arrogant take 80 . 6 multiplied by 1 . know what we have to do 1st thus so convinced that and multiplied by 1 . 2 to get our hands on so we get this in specific purposes we need added 0 and so we need around this city 366 and we have that at the end of the war in the north of year although the union of knows I couldn't do that because the common itself would be aghast I could ask you for the molded carbon which if I did that you could take this and how would you find Moses H 4 you have to fill an ideal gas off-site activities which entries vying temperature things like that and then you would know that however many moles of nothing there is coming all the carbon with every 1 so I can go to malls of the individual elements but I can't go to up partial pressure of a bit of a liquor license but it isn't so we converted to decimal careful you know single-person sometimes people miss the 2nd moving over part of it we multiplied by the 1 . 0 8 yen to their answers and we rounds youths precincts and Eric Seidel to sink face this time In the last 1 so once again we convert to a fraction we multiplied by 1 . 2 atmospheres In the rate come and if I were to say what is the mole fraction of methane receipts for you have to calculate anything for a let's asset right from the beginning I give you this problem the Irish exemplary lots and lots of times in multiple parts of the question 1 thing I always said is you know I all of the cell and I said What is the mole fraction each gas and what is the partial pressures which will more factions the that would be it's right here in this 1 it would be the point 8 6 in the summer .period 0 8 9 summer the . 0 2 5 so if I give you if I give you the percentages turned into enough of what the maximal faction right that's why we multiplied by Whitaker mole fraction we multiplied by a report of it are infamous for example now he should excited no grounds the happy again so there's a little picture here which I think probably got added after the examiner after it posted this so I'm on museum in a little bit of Colleen having his amounts you can see it on this is because of you know this is a little bit of a confusing said but it's a very small 7 something that you can do and what we do you know problem home but definitely alive so we have a sample oxygen gas collected over water so what's happened here is some sort of reaction is going on here some sort of reaction that makes oxygen gas so in this case is a little beaker were something's going on a dealer time this will happen is you can bring something inmates yield to on some this is a way of measuring how much of a gas comes off a reaction which is useful if you're trying to figure out something about other reactions happen maybe you wanna know what per cent yield you wanna know something reaction you need to know what all your species are you need to know how much product get each 1 while this is the 1 way that you can test for oxygen bars you can measure oxygen isn't that's the only unprofitable so what happens is you have something going on here you have action happening oxygen gas comes through here it's really place virtually dull and that bubbles up so you added to that originally was completely filled with water you haven't you can place merged with water the stick into on a beaker of flattening the water here and then the only area in here the only gas here comes from distraction which all the oxygen sizzle in the setup of and this is this is I don't think you lenses in Latin was enacted in last few years by this is something a lot of last year so what can you do with this if you have this is not saying you know you put in a graduated the area graduated on so and you can measure the volume do you measure the temperature after so you know a lot of things about the system and you can measure how many moles of gasoline and that's what we're going to do this problem when you try to figure out how many rolls of oxygen team offices this reaction so when we say it's collected over water this is how they actually go about doing it they have a cylinder filled with water and they put the 2 men the gas bubbles through and then you can as long as this is not like some sort of graduated system you can see the volume of gas :colon so I still went back to school ghastly way what that means is that it has water vapor and it's not pure so if you take a you know a tank of oxygen that it that you don't want any water at all they would have done something to take-up of water vapor in this case it's sitting over troubled water rights we know that water evaporates mean all that water has a vapor pressure that if you put some water down here it's going to evaporate if you put a cap over at its domain condensed evaporated you'd think so there's there's lot of purring here so that's going to change the volume will soon at
2 things right we have water vapor and we have the oxygen down the 2 things that we have to worry about but those 2 go to combined have a volume of 7 . 2 8 set the total volume and we have a pressure of 1 . 2 5 and that the total pressure if all the water is removed what volume of a dry oxygen gas occupied at this whole new set of conditions so we're taking what we just learned that all involve partial pressures Eleanor combined with what we did last class where we went through and out of the final an initial conditions so what going on here is tough questions so just to make life a little bit more fun I also give you 2 in the wrong units so that we could practice player and the units sold this right here Delta water vapor right as the pressure of the water so we know that this pressure is going to be with the water is so then how do we go about finding the pressure of the oxygen he initial pressure oxygen so traders on a different way we know what pressure total Hassani the pressure the addition of all the gasses that are in there so what is in this little was in the speaker is here for gaseous oxygen so we know the pressure oxygen plus within our getting somewhere right because we have less we knows we know pressure totals 1 . 2 5 baht and we know our pressure water is 23 . 8 millimeters of mercury so we can find the pressure oxygen so it doesn't matter where getting closer so 1st we have to do something unit issues so you can really switched to pretty much any unit you want here I happened to switch everything to wrote millimeters of mercury it's the fact that she will put to 5 soaring and take 1 . 2 5 in ending to convert that into millimeters of mercury you could convert it the other way if you want it and of course all of these the conversion factors argument wanted exams don't spend any time memorizing them but so now we have this and we can write down the value In and Out is a model of delegates hadn't had a look at the picture OK so that once again is going to be a total pressure OK so now we can start filling in the values we need so the pressure oxygen so just for the cleanliness of work purposes and a drawling so we need no pressure oxygen and we can get back to this equation right we know that our total pressures only equal to the pressure to gasses so How do we get our pressure oxygen C T and then what do we have pressure of water good we subtracted it's only about now this we switch for units around for this purpose we can go ahead and this village now something that's worth kind of doing up here because we're going to be doing a lot of calculations with things that we calculated is to watch the same things start using your underlined method we have underlined the last significant ones you can keep track of what's happening here is way too much work to try to new traces the otherwise so I won't go through will fill in pressure of each 1 To the the get around every single tiny fill-in To be honest I tend to just save everything in my calculator and then for the sake of units so we can get our hands now I have to pay attention to sing things a little bit here was wearing around 2 so I'm hearing 3 and hearing tent so it's useful multiplication and division you're right with 3 break hazardous three-hour lowest numbers 3 saying things but this is a modification of the it's attraction so we're to our lowest digit so are 10th place that so so that the pressure of oxygen we done now all right this is the pressure oxygen under what conditions b right this is a condition at 25 degrees and this pressure there exceeding the 1 . 2 5 pressure told in that volume that's no accident that would eventually sorry I said interchange area because reality if you're gonna do this probably wouldn't you would change the situation probably would end up today in order to drive a gas you would have to do something to it in so that's going to change a conditions around the world so this is what we're India were nearly the exact same thing that we did last class so this is going back to the material that in we always started from this equation right because we figured Well we start with everything changing and we just crossed out whatever doesn't change so we start from this 1 more time now the next part about this do we have to worry about the fact that millimeters of mercury now all right because whenever I plug in here this just what's going to come out for my final version so that's not a big deal only exceeded that here we we do act acted to worry a little that we have to convert from 1 or the other so it doesn't matter what you we put in doesn't have to be hemispheres doesn't have to be mm mercury but it's got to be in the same thing now are volume so let's go through and convert all this resolving forward variable the until so will fill everything else in so Rp 1 comes from here now I think in this case I converted everything millimeters of mercury again I was apparently in a millimeters of mercury that on Thursday ,comma
rule not I'm going to be a little bit wheezy vibrating units perhaps in so this is a millimeters of mercury now are V-2 Hervey 1 1 is everyone at that time so we'll Henry pattern instead hindsight Natalie's variances too complicated a problem so that everyone now a N 1 do we have to worry about any here know that it's canceled out so we don't have and we don't need to worry about that because we are not changing so that goes away so Rt 1 odds Archie changing that knowing so and as the villain 25 years and right no rightly interview Calvin don't forget that it's it's really the most painful mistake after agreed on anything because we don't know the difference but if you forget that it's wrong to do so at the time but you spot Peter doing obedience the shortest given so I'm just gonna fill 1 . 0 7 and go about my Mary rate right now so we need to go ahead and we need to convert this so that's an 18 so he fell down 18 here we fell in a conversion factor here you can always do this on a different she if you want to and fell in whatever way you prefer we fill in details and we fill in the final temperature good so once we go through all of that and we do the algebra which like at the Eldoret was quite honestly the easiest ways to students at your calculator we have the 2 is yield 8 . 5 0 litres knowledge sentencing for examiners last part so we know that this was just right into is of that and actually just it's not wrong in the Cross offering to 19 8 for the sake of I'm going for entering things because we know Oregon Indiana once digits here now what they're saying things here we took 37 and we added
to 273 cellulose relatives and friends now it's really terrific so what have a significant save situations so now we have promising things here 4 3 savings seriously rethink things here 3 this is actually 3 by definition history and 3 Sewanee . 3 down here so I'm McConnell underlined their to play so question on the very long complicated problem is a lot of problems you probably are going to have to do to really get go through and do looking at the notes do not looking at the notes that constantly referring to them off and on for help and maybe do again on your own you know 3 or 4 times before you really get it is long and complicated but it's really just combining a bunch of things that we know with 1 using phrase I give you this new experimental side but we know that whatever the oxygen is whatever that little volume is is just start to pressures added together we know let them know that if we want to find the pressure oxygen after last class last 5 minutes we know that we can is subtracted from the total because only 2 component straight it's only water and oxygen so we subtract that define a pressure oxygen now back to what we did for the whole 1st half of the 4 hole 1st half of class last time and we said OK well we have an initial set of conditions that we have a final set of conditions let's solve for the unknown but the any question of a foreign land you maybe a little too lots of questions and that's fine we can really is about 1 out of recession or something by next month right so into containers connected by about that can be opened initially the pressure and volume there is marked by find that finds the final touches after the novel part is opened but so this could theoretically you really complicated problem but luckily Noland war makes it simple for us which is really nice so we can treat this as 2 completely separate problems Warren do is we're going to pretend that we open the styles and that there's nothing here that there's no Garcia that it's just a matter and we let the pink coming to here in equilibrate bring to pretend that I don't have a problem then in the 2nd half of problem were going ahead and pretend that then goes into here but this goes into a completely empty container over here and a second-half about what that's gonna 1 of doing is giving us the partial pressure so if we have a partial pressure each gas-hungry friend finally that we decided together so was going and do that so let's start with the kingside so what all is changing here didn't say anything about the temperature now we assume it's constant is the mall's changing really think that durable and a little angry polls again this is a tricky question so they're right but you know coral enters a right was seen off your understanding things so why is the animals gonna change were combined with pink and blue there enough time at the end of that we're not talking about the blues we don't care at all we care about is the thinking a change and it's not 100 taking away without added so the 1st she assisted on it so what we have to worry about changing that just kidding so it becomes clear when we won because key to victory I am so now just in some numbers so Rp 1 another the 1 every year now peaches or solving for whenever the 2 is a former leaders no it isn't 5 leaders right assist total were added together we're saying this I think 1 can just spread out over the whole space and nothing it's way that's kind of work tending and so in that case is going to be 1 plus 4 so we solve them and we get our 1st it but no 1 at the exact same thing for the Blues site sold take like a minute yourself into it sitting in right did figure out find the total pressure as well Oh yes the Sunnis and initial values so these are the initial values of the pink in the initial values of the blue part of the 20 more seconds conducted the ,comma seconds to city the same thing and it went after pressure from Luanda there a great did so community is 1 volunteer variables 1st issuance finalists 5 years as well right of the academy having said that as our partial pressures sell in this case I just told you to find the path the final pressure but the easiest way to do it citizens a partial pressures there are actually other ways to do it as well but added so let's go ahead and add up I want to be a two-point 2 0 at all right question on that 1 yeah I know I did the hard version even 1 that the date of the next 1 however worried about the hot really interceded to give it a little bit of a breather between Suharto and that the real reason for doing it here on it but I think you'll be really happy with this hard-won Minnesota that put it up and you see the format you'll see why any different from last year but not lightly 7 but president you don't know what the other homework program this summer classes use that that that's where that from on it yet this is done your homework so you have to have a children from you hopefully because this is the year the long question little our rooms on their habitat is the amount and move around a little bit but this is the same size and that's what kind ceremonies original and this is more intense version so we had an to fizzle also went public service announcements for remember all the fundamental stuff that you may have liked said while I'm mean just remember this stuff that make sure you remember that picture you go back and do this because this is a lot of the fundamental section that we sort of talked about a lot and lecture on because the Spanish Cup warning you was gonna come back and factor for while it's here so we have to balance
the 2 walls they're connected with an 0 1 0 2 In the last situation in reactor right leaders plan together lot around and found a new pressure but in this case they're reacting they're forming a new stub upon insult it gets a lot more complicated now now we have to deal with a bunch of strictly on the tree as well so we need to find the proper the pressures of each 1 but to do that we have to find the more with each 1 1st and defined the malls in each 1 would we have to go are due adding in a reacted completely formed to NO 2 Ingrid had none of this and analysts no it's probably going to happen I'm saying that there's going to be a Romanian region so that the 1st step but surrender finally region so we need to find the malls of that each 1 of the starting the finals of NO and moles of 0 2 so that the 1st step so the find animals about 2 action with singles and offers what aquarium used finals what we have we have some volumes and we have some pressures we have some temperatures so as that like I don't have do we have to worry about our units in the situation do you have on the have particular units that so that the atmospheres with straight so were sent there so not a big deal so we sell everything in so this is all taken directly from the the question landscaping the units of our because honestly we were really short and review of certain
have that that's just calculator button-pushing and we get this I am so that older man now do we have suffered well if a final in the region we need malls the other 1 right so exact same thing and sapling was nice and only from the DAB everything in their units and is very very long hard problem I decided I didn't want the nature the previous operated that's all I want to thank the center I so now we can only match at reacted stage there isn't a bunch of different ways of doing that and everyone has a favorite way I think in this 1 doing logic is the best way of you can choose to do it mathematically the 1 that you can ever hand-in-hand so if we look at this if we have 1 oxygen company and I was doing it 2 If we have 5 accidents from me and I was doing 10 20 40 so that had right how many do we need double not we have bad so we'll get oxygen do we have double the amount of and all that we need not so well once the nearly region I am so college and Oregon have at the end reaction 0 right so no malls no pressure amid next part we need to figure out how much you know to
order have and how much would also I mean we are actually a lot when we were were the questions soul which will make it again and so on that is that we have more oxygen than what we need right yes so that we wouldn't have any oxygen loss yet so we're going to have to figure out how much until we make and how it oxygen nearby so that the next polls so it it doesn't really matter which already do it and I think I fumbles loath to 1st so we're going to find moles 0 2 left hand finds moles of N O 2 earlier let's do an ode to 1st Waseca easiest so and we used up all of our more than an hour How much NO to that's wants the breakdown more but Senate and 1 mole very big 1 I haven't won more than on how many more 0 2 1 bed firefighters make 5 great this same an obstacle the coefficient of the city so what we're going to do here it is if we know how much an to is made we know how much and always started with which we do we know how much N O 2 is made it's the same amount look up so we just write it down sickly we just take our amount of end of restarted with and we break now seen all the more complicated right because we know how much we had to begin with and what we calculate that happened in this reaction how much we made how much we use data how much is left over 121 1 calculation using distraction how much was uses up right we shouldn't we know that further if this has to that 1 of a mysterious death we have 5 at 10 . 5 already used up all that sold more than did do then is to find the final mile oxygen were intake are initial out an organist subtract away the thing that we use them so but see that in was just a little ass underneath malls her final just to make a super-quick soul of obviously would defy gravity designed exam you wouldn't need to write down all the sentences understating the 3 soon you go back and look at this you know what's going on so more those who left over how much did we start with we started with this trade they were innocent track was used look at how the fear was used well we know that can do this as a sideline decades sometimes we know how NO to the NO we started with right now How is the malls of NO animals of oxygen related Mauricio so writing is that really big so you can see it and I'll plug it into the smaller area sluggish everyone to see more than an hour ago here the oxygen will go here and what is the number that accident once we got that from where the equation and here too OK so I just wanted to ride out big and then I'm gonna filet in the equation on the notes have been taking as well the Just the it's getting tough to see so we took a toll that we started with artificial mound it we subtracted what we used and when we get this then we end up with 0 . 0 8 1 so we have our finals oxygen we have our final moles of N and O 2 and we have ofanimals NO it's 0 it's a word that there now what equations do we used to go ahead and sulfur now the exact problem that we had before the problem where the question of that the right now we're at the G 1 the 1 equals he won everyone over and 191 question and we have to look at what's changing so if you don't go back to the question in which to look at everything that is isn't changing we can sell everything and and if so we're still OK protect and so when we got is that we put in our final amount of moles I thinking we do this for each 1 effective until has and we feel everything is so now this becomes a scavenger hunt right now I have to go through and figure out where everything is coming from make sure you grab all your final values and not here in between values so this is just ah make sure you remember after all of this work being done to convert intended Unocal that high the deed get things like this after we don't gone through everything we're going to walk through it a little bit here once I finish it as well as we can talk back over everything that we do so now I'm just filling in numbers we've done all the hard parts and we're still in everything so when you fill those into the calculator and endurance I can't read the site no of course you know that your homework values are going to be different than this so don't go filling those and right away you know that changes your numbers on such a toll of pressure let's go back through and talk over what we just did in the last like in OK so we started by saying well in order for unifying the final pressure I need to find the initial pressures so I know all of this detail I can use people the Nazis and I can solve for my moles once I find my moles I can use all of my knowledge that I remember from the 1st week of class and I can use the economic treatise sulfur 101 ingredients I know what's not going to be there till how much of the nominee region is leftovers and how much of the product they made and then after we have that we have our malls of everything so we still know that we have quarantined the we can find out the problem but now we found our final balls and we can fill in our final malls into the people that actually equation again really as far as doing in taking energy using you know the conversion just like we did before and you have to go through malls so you can retrieve animals you've used a commentary in the newspaper everything back into action plan of the
missile and that happened up and thus the consecutively
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Formal Metadata

Title Lecture 20. Dalton's Law of Partial Pressures
Title of Series Chem 1A: General Chemistry
Part Number 20
Number of Parts 23
Author Brindley, Amanda
License CC Attribution - ShareAlike 3.0 Unported:
You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal and non-commercial purpose as long as the work is attributed to the author in the manner specified by the author or licensor and the work or content is shared also in adapted form only under the conditions of this license.
DOI 10.5446/18985
Publisher University of California Irvine (UCI)
Release Date 2013
Language English

Content Metadata

Subject Area Chemistry
Abstract UCI Chem 1A is the first quarter of General Chemistry and covers the following topics: Atomic structure; general properties of the elements; covalent, ionic, and metallic bonding; intermolecular forces; mass relationships. Index of Topics: 0:00:23 Dalton's Law of Partial Pressures 0:02:43 Mole Fraction 0:04:41 Working Out Partial Pressures 0:13:33 Volume of Oxygen 0:28:59 Finding Final Pressure 0:35:19 Pressures of Mixed Gases

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