okay guys today the experiment number five and this is the generation remember guys in the previous experiment we did a titration but I was a little different titration it was an acid-base reaction and so the chemicals were an acid in the base now in this situation we're going to have a redox reaction and so what we're going to have here now as the oxidizing and reducing agents they're going to react and pretty much one will pull electrons from the other and that will be the essence of this chemical reaction strands from an electron in other words now so but before we can react now our oxidizing reducing agent we first in the first step you're going to see how I'm going to conduct this experiment I will be acidifying I'll be pruning I will be reacting the sodium hypochlorite with HCL just to make a hypochlorous acid if I don't make its my next reaction will not occur it has to be definitely in the acidic medium also I'm gonna make sure that I'm gonna head well there's gonna be added to HCl anyway so this reaction this number two will not go guys unless I'm going to acidify this sodium hypochlorite now in this reaction now in the reaction number two hypochlorous acid is the oxidizing agent and it's going to oxidize this I minus and the products will be triiodide right here two chlorides and h2o guys and the water now so why am i doing this well eventually I'm gonna have this sodium thiosulfate it's a titrant and I'm gonna react now this triiodide to anodite which I'm gonna complex with starch because anytime we do titration guys we need to make sure that we have something colored the solution has to be colored and the way we can achieve that column to the solution is by complexing complex to make accomplice now this Chie iodine the starch and so once we the storage we're going to form this complex that will be dark blue so now we've got a caller and when we're gonna finish their training now with now this triiodide starch complex now with sodium thiosulfate this is will be another redox reaction here another enix reaction this will be reducing age of this will be exercising agent and so what's gonna happen here once this iodide is gone by reacting with the sodium thiosulfate that's what I know well first of all the color will disappear right away guys and you will see the titration but does that this should want drop of this this whole thing now will be turned into the iodide colorless solution that's what I know where to stop that means I achieve my equivalence point guys and so that is important so that will be the end of my titration wants to see I go from dark blue collar to the colorless color okay now how do you do the calculations now the calculations guys are not complicated it's just the stoichiometry as we've done in chapter 3 and so how does it sound so geometry warts in here as you remember in the previous guys in the previous presentations guys I use this formula near very instrumental guys formula and your titrations molarity is equal to the ratio of number of moles to the total volume of the solution here now if I know the molarity now of my thiosulfate I know because I prepared it and there this that would be your molarity here moles per liter of the total solution here I know this if I know the volume that will determine by the titration experiment when reading the burette for the determine the volume of the titrant that will be my volume whatever the days there is that just said liters of the titrant that would be guys determined from my titration experiment so that's the number you're going to be plugging right here from the burette but remember guys that will be milliliters there but use the convert to liters that's why I said liters of the titrant very important once you do liters liters you can cancel these to cancel these two I have to cancel them forgot so liters and liters will cancel here and so what you're gonna have in the first step guys of determining the mass of sodium hypochloride this is the final the final product here the final amount of the sodium hypochloride dissolved will bleach that's what you need to determine guys this is what you're looking for to plug in here in the next step but so how do we do this mass of sodium hypochlorite again we're gonna use this formula we know the concentration of my titrant here I know how many liters were used up to react to react here guys so I got the moles now sodium hypochlorite or my next step I have to do this to geometry here look so I got now two moles to moles right here see this to here guys - there it is same units unit analysis cancelled will react guys with wand you see this empty space here means one one more of triiodide ion there it is I put right on top here cancel cancel so now I got the moles of triiodide area so how to finally go to this substance I go to the serious steps of stoichiometry to get here so let's follow my steps here now hello so one mole of tri iodine and iron there it is now reacts guys actually produced based on one more of this hypochlorous acid right here and that's why I want to one ratio again because of this talking magic coefficients guys here next one so now I know that my one mole also years either's wanted here of hypochlorous acid will be produced based on one more you hypochloride and there is my multiple ratio here this has to be cancelled now these units have to be cancelled here and here and so when I gotten out here moles of sodium hypochlorite if I have the mole stopped sodium hypochloride it is very easy for me to find the grams all I have to use now my molar mass conversion I know one mole of sodium hypochlorite will be equivalent to its smaller mass and I on purpose did not calculated because I want you guys to determine it using the periodic table so once you got the now the grams of the sodium hypochlorite you will need to find the percent concentration of it in their regional bleach solution how do you do this well we know the percentage is nothing else as the part and the part will be our grams of mass of sodium hypochlorite it's also sort of mass of the solution in the whole thing here and since we prepared 25.00 ml of the stock solution so that's what I'm going to use the mass of it but this is a Mel how do I get now from from ml to grams I will use the density formula density is equal M over B and in the math there will be a density times the volume since the density guys is one point zero nine gram per ml for that bleach solution stock since I took our 25.00 ml from the stock I can find out the mass of the 25ml of the bleach and time stand remember guys in the previous video I talked about the dilution there was a one dilution made here and it was one to ten dilution so how did I get the 10 and again we're going back to the formula here c1 times v1 is equal to c2 times v2 and we don't know the concentration in this stock solution here that's why we'll be left on the left hand side and I just cross multiply just brought the v1 to the other side to find out the dilution factor here while since I can find out now the diluted the concentration from the titration and I know the V to be true guys was two hundred fifty point zero zero and mal that's where I'm going to pipe at my solution for titration you will see that in now and one of the steps and I buy pad at twenty five point zero zero ml so 250 divided by 25 gives you ten and that's how I got my dilution factor 10 here and then of course to find the percentage of the multiply now everything by 100 and that's how you would get your final answer and now guys in the next video you'll see me performing this titration and you will be able to now general the data and you will be able to calculate the final result based on the data so I'll see you guys in the next video alright guys and now we're going to do the practical aspect of this experiment we're gonna do the titration now so the first step is to prepare our sample before we titrate we use diluted we talked about it guys we need to double it by 10 and so what I'll do now is I'm going to pour this sample of Clorox this is my undiluted sample into this beaker and I'm going to pipette now 25.00 ml from it into this volumetric flaps 250 ml and remember guys we did the demo on how to pipe at and this procedure guys was number three and I went through great details and I'll bypass now you have to just watch me how to do it the correct way so as always I pass this line because I need to prime the bubble so now my ammunition is touching the line and now I have 25.00 ml in this 25.00 about a metric pipettes I got some really faulty here Bob so I'm gonna have to work with it but I'll manage to see how it's not really folding guys to vacuum in here so it might happen to you just so you have to come out of this situation so if I have to do more samples that will definitely would replace now as well because it's faulty one two three four five six seven eight nine ten and the next step up will have to now dilute this 25 ml up to this line here in and we've did it guys before in the previous experiments the previous titration experiment so that I have now the original undiluted solution diluted so we'll get a beaker here these - baguettes - fine - want you to somehow deeper I found it now so I'm gonna raise it real quick and again guys you may not have everything ready it happens [Music] so once I'm approaching now this line I will have to do it drop by drop so I need to get away transfer pipat's and I have to find make a fine a jocelyn here so that the bottom of the meniscus is just touching that line alright so that looks like one more drop is needed here almost there and that is almost perfect for my drop and again this is not that crucial year but now I got to achieve my the bottom of the meniscus now touching the line so I know I have the total volume of the solution 250.000 I put the stopper in and they just twist it slightly so it doesn't leak and I'll do now 10 times barbell up and down six seven eight nine ten to mix now my solution is mixed homogeneous solution here and I bring it to the next step okay guys so in this step now what I'll do is I go to pipette now 25 ml of my diluted solution here that are prepared in the previous step and any time guys before you are taking any aliquot from from a solution you always have to mix it so simple number one as you can see guys that changed the vault there bob was no good so this one looks like it's working much better [Music] so now I'm delivering 25.00 ml of the delegate solution into the 215 or my flask [Music] [Music] [Music] [Music] okay guys I just finished the ripening 25.00 and mellow my diluted sample here so I would not need it anymore so I'm going to put it aside and now I'm going to prepare my burette with my titrant which is a sodium tyre sulphate solution here so this is my sanitized sodium thiosulfate solution here sorry it means that the burette with the distal water so I just needed a little bit now of the titrant solution to saturate the walls of the burette with this solution and after the instant well fill it up and I'm ready for my next step so at about five ml of the titrant solution now forgot to close the valve there you go so now I just want to arrange the walls of this view at from any distal water that I used to clean this burette okay so that looks good so now I'm gonna get rid of this dinosaur fit solution here okay guys and I'm going to use some sodium thiosulfate so even though this is clean occluded with a distilled water but I have some residual amount of distilled water so what I want to do is I'm going to get shredded now of this distilled water with the using now sodium thiosulfate solution here about 5 ml and I'm going to do the same thing as I did in the previous video I'm going to now saturate the walls of this burette with my titrant solution I'm gonna add about 5 ml and I'm going to now roll it this viewer out so that anything that is not sodium thiosulfate is being dissolved by sodium thiosulfate and I'm now going to get rid of it okay so heal the patients here I'm gonna make sure that everything now is out and the only thing that stayed in here now is the titrant sodium thiosulfate okay so I got tricked now this solution I'm gonna add sodium thiosulfate I'm gonna fill now this burette with the sodium thiosulfate so that it could because it's ready for the next step as always I want to pass that line of zero because I do have some baubles in here so when I make sure that before I do the titration I got rid of all the bubbles in here so I usually open it up and top it slightly gently on the sides of the burette just make sure that the titrant is not spilling over and going into your eyes it's very important so you don't have to be you know sparing this titrant solution but what's important here is to make sure that there are no bubbles ever see any more bubbles in here so I'm going to make now more edition of this Titan solution that are past the zero line and the next thing I'll do is to adjust now the bottom of the meniscus to the zero line and so that's what I'm now focusing and doing here all right perfect so now the bottom of meniscus guys is lined up with zero point zero zero so now I know I'm starting with the zero and males in here of my titrant and now we're gonna go to the next step okay guys so now I'm gonna follow the procedure I need to add certain reagents to my diluted sample I have to prepare my undiluted sample so that I can trade it properly so my first step here is to add 15 ml of distilled water now this is not a critical step here in terms of getting executive exactly 15 ml so I'm going to just approximately 15 miles in here so yeah don't go crazy guys when you do the step has to be about okay this is actually exactly 15 ml all right so I got my water araignee and so I'm heading out to the for samples so my next reagent will be a 20 ml of 10 percent potassium iodide solution now this iodide solution is very important this is the excess reagents and again if I had a little more that's fine I don't want to be adding less of this so it tells me a 20 ml hey guys look at this now this is a learning moment here once they prepared the burette I can see it's dripping it's not properly sealed so what I have to do now have to recraft this burette again so I have to do the same snap as I just did before this is a bad burette so when you encounter this kind of problem you will have to guys use a different burette so again we're going to replace this Buuren guys so in the moments I have to again we prepped everything but I'm continuing now adding the reagents my to my sample number 1 again I just added 15 ml of water my next step is 20 ml of 10 percent ki so my potassium iodide temperature solution is right here and again remember guys every time you take out chemical always mix [Music] all right this is perfect 20ml [Music] okay now my next step will be so I had a 10 M 20 ml of 10% potassium iodide and the next step after 2 for 2 ml of the starch solution in the 10 ml graduated single cylinder I'm gonna skip the step guys I'll show you why at the end of this titration this is not a critical step in this at this particular Junction here so I'm gonna go now next using a 100 ml graduated cylinder at about 20 ml hydrochloric acid now this is a very important step now so I need to turn my sodium hypochloride into the into the acids into the HOCl hypochlorous acid and so this step is important so I'll do now 20 ml 20 ml of hydrochloric acid right okay all right guys I'm ready for the titration so again I will have to repress now my view right in here I have to choose the one that does a leak so I'll see you guys for the next step what I'm going to perform a titration okay guys so now we're ready for that - to titrate our sample here I we prep the pure ads I've got a different one now doesn't leak so I'm ready to do my titration so now here I'm going to add sodium thiosulfate to the point where I see a pale yellow color once I get to the pale yellow color that's where I'm gonna add the starch to complex now the triiodide ion with starch and it will form this dark blue collar and then after addition of a few drops guys at this titrant you will see how miraculously this dark blue color disappears and that will be my endpoint of the titration all right let's do it and again I'm pretty confident here to add a certain amount of ml because I know the color I'm going to I'm going for so eventually I will get the color similar to this one here and again if you want with Daiichi if you're going to go beyond that yellow call a kind of pale yellow color what are you going to add the starch guess what's going to happen you're gonna have a colorless solution that means you pass your hand points so you've got to be careful here guys and then what I'm gonna do now is I'm gonna have my star traded I'm gonna use up again to amount it doesn't have to be exact at or male this is just has to be added an axis I'm gonna add a few more drops again the Paleo car the pale yellow colors is now that crucial should be really yellow okay so I'm at the point where I'm comfortable now to have my starch there you go so now I formed the conflicts which are with the starch and try diets iron here and so now I'm ready to get to my end point and the end point will go from this dark blue color to the color of the solution all right let's proceed I can see already that I'm very close to my hand points I see my Carla solution is not being developed here in the middle inside the titrant see I'm almost there and here you go so one more drop I think we'll do it guys there you go so now I can read my volume here and we get now our first data point so this is now eleven point seven zero eleven point seven zero alright guys so I just read my volume of the titrant eleven point seven zero so I just put it down in the data table eleven point seven zero and now the initial value was 0 point 0 0 ml and so volume delivered is nothing else is just eleven point seven zero ml so now I'm going to move to the next step I'm going to do the same thing with sample number two and three so my initial volume here will be now the found final volume for this first titration here and that will be 11 point seven zero so I'm going to prepare now the second sample as it did the several number one and it will proceed to the titration again okay guys I just added the same reagents as it did for the sample number one and it's ready now for to be titrated so again my initial volume was guy 11.7 zero so that's where I'm starting my second titration so the difference between the initial the final will be me the volume deliveries huh what i forgot this i forgot to add this now to amount again that happens it's no worries there it is [Music] it looks like one or two more drops and we finish yeah there you go to second drop and we finish you all right well I'm gonna read now the volume because it still has a little blue collar here and so this looks like it's 23 points 22 3.3 tools but again it's one one more drop there we go so it's all finished so let me do the final reads and that looks like twenty-three point three five okay so I'm gonna double-check now my number here just to make sure that I got it right yeah it looks perfect here and that would be my initial burette value for the next foot sample number three titration okay guys so now this is the last sample I'm gonna do the same thing as added to the previous ones I'm going to titrate this sample my initial volume of course twenty three point three five which was the final volume of the of the previous saturation now this story with this starter gears is behaving today but it's okay we're gonna persevere with it today we just put it in the center okay there we go so that's at some titrant right now okay more or less ready to add the starch solution here now to complex that triiodide ion and so now we're going to go to the card on the solution and that would be the end of the titration to sample number three there we go all right so let's read the final value this one is looks like thirty five thirty five point one zero No and so all I have to do now is to subscribe my data onto the data sheet and that would be the end of this experiments okay guys so the now we're going to fill in our data in the data table here so I got the density get to bleach is one point zero nine grand per ml the volume of the diluted bleach used in a titration 25.00 the concentration of sodium thiosulfate this is where I guys got it from the bottom here went to 6:05 now I'm gonna transcribe the data from the experiment so for the first one I had a final well first initial burek value was 0 point 0 0 ml eleven point seven zero final one so of course when you do the subtraction eleven point seven zero V final minus V initial you will have eleven point seven zero ml now the next one was eleven point seven zero was the initial volume for the second trial the final was twenty three point three five now the difference will be eleven point six five and then the for the third one will be twenty three 35 ml was the initial volume the final was thirty five point one zero ml and eleven point seven five was the difference the final minus V initial so all you have to do now guys convert these volumes to leaders the leader of the solution and then remember guys how I explained you how to use now this data that you obtain from the experiments I went step by step do for you guys to calculate the mass of the sodium hypochlorite so please go to the part of the video and use your data plug your data in and get the final answer and so now what you guys have to do also is to contact your professor for any additional instruction on how to complete this laboratory experiments you