Purifying Sulfuric Acid Drain Cleaner

sulfuric acid is used as a drain cleaner because it's pretty good at breaking down organic material like hair and other things that might get caught and drain the sulfuric acid based drain cleaners can be sometimes hard to find but I actually managed to find it at quite a few stores unfortunately the drain cleaner sold in most stores is discolored and it's not concentrated it's usually only around 93% instead of the concentrated 98% so to get this sulfuric acid in good shape we're going to have to concentrate it and purify it there are two main methods that people use to clean and concentrate the sulfuric acid the first method involves adding hydrogen peroxide to the drain cleaner and boiling it in open air and the second method involves distillation for me I think that the distillation method is vastly superior and I'll touch on this a little in the video the next point to address is why do we want 98% sulfuric acid and not 93% and why can't we get to 100% the answer to this is that there are a lot of applications that you can get away with using 93% but there are some cases where 98% is absolutely required the simple reason for this is that the 92% has a lot more water in it and for some reactions which might be water sensitive this can pose a problem so why can't we get to a hundred percent the same issue pops up as in my in hydrous ethanol video and the problem is that at 98% sulfuric acid it forms an azeotrope with water an azeotrope occurs when the ratio of one component to the other is the same in the liquid form as it is in the vapor form so when we're at ninety-three percent sulfuric acid and we boil it it'll be mostly water that's coming off but slowly as we get close to the 98% we'll get more and more sulfuric acid coming off eventually once we reach 98% the vapors that come off will also be 98 percent so at this point it's called azeotropic sulfuric acid and this is the most concentrated will get and this is what I'm after there are some ways to get it to a hundred percent but it's really not worth your time the procedure would be more or less the same as Mayon hydrous ethanol video except the drawing agents that are used will have to be much more specialized anyway that's a little bit of a tangent and kind of out of the scope of this video so without further ado we'll get things started so started with the classic method of adding hydrogen peroxide to the drain cleaner I don't really think this method is worth it and I'll explain why later but the ingredients that are needed for it is just hydrogen peroxide and drain cleaner I would use at least 30% hydrogen peroxide but the 3% might work as well to start things out I pour in some of the drain cleaner into a boiling flask it's important not to fill it more than halfway really because a later step is to boil it and we don't really want a risk of having hot sulfuric acid flying out this flask is about one liter so halfway is about 500 millilitres of drain cleaner using a magnetic stir bar we stir the drain cleaner and I add some hydrogen peroxide to a beaker I started out by adding the peroxide to the sulfuric acid drop wise but it proved to be too slow I was trying to go as slow as possible to limit the amount of water that I added but it seems like pouring it in is a good option as well I keep adding more and more and strong stirring the sulfuric acid starts to clear up after each addition of the peroxide we wait a little bit to see if it continues to clear up the color will slowly change from a dark green to a yellow and then it'll be colorless what's happening here is when we add the peroxide to the sulfuric acid we're making a dilute piranha solution so here we can see the equation of the sulfuric acid reacting with the peroxide to make something called Karos acid Karos acid is just a common name for it but the chemical name is peroxy mono sulfuric acid what's interesting is that Karos acid is actually one of the strongest oxidizing compounds known a solution of Karos acid is commonly used in the lab to clean things and this is commonly known as piranha solution I made a video on piranha solution about a year ago and I'll include a link in the description but I do plan to revisit it in the future so that's enough theory for now and now we'll address what's actually happening I guess the first question to go over is why was the acid even green to begin with the answer for this is that the companies that make these drain cleaners include things called inhibitors these inhibitors are actually organic compounds which prevent the sulfuric acid from corroding metal pipes when a drain cleaner is used it has to sit in the pipe for a little while and without any inhibitors it might attack the pipe and degrade it okay that's cool we have inhibitors in our acid we don't want it but how does this piranha solution get rid of it well as I mentioned before the Carrows acid that we're making is a super strong oxidant and the inhibitors are organic compounds when a strong oxidizer is mixed with an organic compound it usually undergoes what's known as complete oxidation when a carbon compound undergoes complete oxidation it's completely destroyed and converted entirely into water and carbon dioxide carbon dioxide is a gas and it bubbles out of the solution but the water stays I also forgot to add that to speed things up a little bit I heated the solution to about 50 degrees Celsius anyway we keep stirring and eventually we'll have a clear solution with a lot of bubbling the bubbles are a little bit of co2 but a lot of it is actually peroxide breaking down into water and oxygen gas the next step is to boil the acid to concentrate it and to get rid of excess peroxide to do this though we'll need some boiling chips and for this I use broken glass I pulled out an already damaged round bottom flask and I decided to sacrifice him for the greater good I'm pretty sure he understands and I was nice and I killed him quickly so he wouldn't really suffer too much once his body was crushed into moderately sized pieces I was ready to move on to the next step the first thing I do is I use a magnet to remove the stir bar from the sulfuric acid we can't use a stir bar because the sulfuric acid boils at above 300 °c and I'm not sure if the stir bar would survive once the stir bar is removed I start to add the glass to the flask I added all the glass pieces slowly but this really doesn't need to be done and they can pretty much just be dumped in all at once it seemed like a lot of the bubbles were coming off the glass now which made me hopeful that they'd work well as boiling stones the entire setup is then moved outside because boiling sulfuric acid indoors is kind of stupid then when I feel like I'm ready I crank up the heat and I start to boil it before we embark on this journey it's important to know that boiling sulfuric acid is really no joke and if it splashes on you it will instantly char your skin I will post in a future video the effects of acid on skin where I pour different acids onto my hand and you'll see the effect so if uric acid doesn't do much more than dehydrate my skin but this is room-temperature sulfuric acid and if it's at 300 C that's a totally different story so for this step the sulfuric acid must be treated with the utmost respect anyway as the temperature starts to rise a lot of bubbles come out a solution these bubbles are both co2 that's being liberated as the solution heats up and oxygen as the excess peroxide breaks down the bubbling will slowly die down and become more constant what we're boiling away at this point is mostly just water and the acid should be slowly getting more concentrated eventually though I reached the point where the bubbling wasn't as constant and I start to get big bursts of larger bubbles crazy bumping can start to occur because now we have a solution of sulfuric acid at around 300 C but there's still water there and it's basically getting superheated so it got to a point where the bubbling would look like this it would not bubble very much and then suddenly boom a lot of bubbles would come off this can be dangerous because really hard bumping can lead to splashing and in some cases it can also crack the glassware after boiling it for a while the water should all be gone and eventually will be boiling away a Z tropic sulfuric acid which is 98% sulfuric acid - 2 % water this endpoint is really hard to tell and it's kind of a judgment call anyway once it's done it's allowed to cool back to room temperature for this method I haven't really come up with a foolproof way to determine that it's 98% sulfuric acid to test the concentration of the sulfuric acid we first measure its density to do this we weigh out 10 milliliters of sulfuric acid on a scale we get that the mass is eighteen point three five grams so this means that it's one point eight three five grams per milliliter to determine the exact concentration of the sulfuric acid we can look up a chart on line which correlates the density to the concentration the density of 98% azeotropic sulfuric acid is about 1.8 for a few points to make is that the density of sulfuric acid is pretty dependent on the temperature and also small fluctuations in density can make a sink it's a different concentration than it is on this chart you can see how the density varies with the temperature and also you can see that the difference between 98% and something like 95 can actually be out of the range of my scale something as simple as adding one extra drop can make us think it's much more concentrated than it is with all this being said if you're pretty accurate with your volume and you're weighing you can probably get a pretty good estimate of what the concentration is the next method is the distillation method and in my opinion this method is superior I start by filling a 1 liter round bottom flask about halfway up with the drain cleaner in the bottom of this flask I've transferred the broken pieces of glass that I used in the other part but I've also this time included a bunch of sand I didn't like how much bumping was occurring with just the broken glass and I found that adding the sand helped a lot just to make sure that it bumped as little as possible I went ahead and added a bit more sand you can probably use any old sand but the sand that I had on hand was actually nice clean pre acid-wash sand so this is why it's nice and white but I imagined plain old park or beach sand would work just as well before moving on it's important to clean the ground glass joint of any sand otherwise the pieces won't seal together so now we start putting together our distillation apparatus and in between each joint we seal it with sulfuric acid sealing it with sulfuric acid in this case is an ideal because since we're boiling sulfuric acid it will boil a bit of the stuff that's in the joints however at this point we really don't have many options i heated the flask using an electronic heating mantle and shortly after heating it the color started to change what's interesting is that hot sulfuric acid on its own is able to oxidize carbon all the way to co2 this is why I said earlier I didn't think the hydrogen peroxide method was really worth it because we're going to be heating it anyway and if we do it will probably oxidize the co2 anyway without the addition of peroxide I also found an extremely important part for the distillation is to insulate everything using something like aluminum foil when this isn't done it's actually pretty hard for the sulfuric acid to make it over to the condenser and a lot of times it just drips back into the distillation flask after a while sulfuric acid will start condensing in the condenser it should be noted that in this case I don't use any water in the condenser and it's more than sufficient to be air-cooled if it does end up getting too hot you can add a little bit of wet paper towel to help cool it down but I don't think it's necessary at this point in the collecting flask will be collecting pretty dilute sulfuric acid because the boiling point is too high and I don't have a thermometer to use the hardest part in this distillation is knowing when the concentrated sulfuric acid is coming over at some point it's pretty easy to tell because there's clearly water vapor but there will be a point where there is no water vapor but it's at something like 95 percent sulfuric acid I think the best method to use is nurdrage method where you watch the sulphuric acid and check to see if the drops that are falling in are of different density I wasn't able to get good footage during the distillation but I'll show you here what it looks like when we mix two solutions that have different densities you can see a lot of those weird lines forming which I'm sure you've seen before when you mix things like hot and cold water so during the distillation if you keep seeing this then the concentration is still increasing repeatedly change the collecting PLAs and only collect a small amount at a time and once this effect disappears then you know you're ready to collect the concentrated sulfuric acid the reason this occurs is because the two liquids have different densities and thus two different refractive indices the two liquids will Bend light slightly differently so when they're mixed we can differentiate between the two once this effect stops occurring it means we're distilling now 98% sulfuric acid so I swap out the round bottom flask for a larger one from this point on I start collecting everything until the end of the distillation now just a few comments about the distillation apparatus itself you can see here that there's just the stopper where a thermometer would normally be and that it's actually wired together using copper wire this was done because the bumping got so crazy at some point that it actually popped the joints apart we can't use plastic cat clips because it'll melt it and I didn't have any metal ones at the time you can see here in the distilling flask just how crazy the boiling god it honestly surprised me that despite all of the sand and the broken glass that it would still boil like this I might have been providing too much heat to it but I found that when I turned it down no sulfuric acid came over the boiling was fine but every so often there'd still be large bumping and you can see the foil move one other thing to point out is that you'll see that the acid solution is now colorless or slightly yellow and it's no longer green the hot sulfuric acid tended to take on a yellow color which disappeared as it cooled down but this suggests that peroxide isn't even needed at least for the brand I used one other thing to point out is that at the receiving side you can see I've set up a trap the trap is an inverted funnel trap that I've used in a lot of other videos and it leads into a solution containing sodium hydroxide this is used to neutralize any sulfuric acid or sulfur dioxide fumes that might escape the apparatus we keep going with the distillation until there's really not much left in the flask so we turn everything off and we let the entire apparatus cool down the receiving flask is removed and Stoppard and you can see we have quite a bit of nice crystal-clear sulfuric acid so here I pour it in directly and replenish my old stock of sulphuric acid what's interesting is that when it's added you can actually see that there's a density difference between the acid I'm adding and the acid that was already there this previous sulfuric acid was store-bought and I think it was around 95% so my distilled acid is actually a higher concentration in another batch that I did there was a little bit of sand in the sulfuric acid so I decided to filter it unfortunately my filter wasn't as clean as I thought it was and it turned the sulfuric acid yellow I didn't really find this to be a huge issue because I imagine the contamination is pretty low but it was still kind of annoying I transferred it to a bottle and I decided that I would use it in reactions that didn't require super high purity the first reaction that I use this in was for the preparation of chromel chloride and you can see in that video that the sulfuric acid I use is yellow just as a final demonstration I'll compare the effects that the two concentrations of sulfuric acid have on paper I'll pour it on some paper towel and see how long it takes to melt through two layers we start with a concentrated sulfuric acid that we distilled and once we pour it on the paper we start the timer from the moment the sulphuric acid was poured onto the paper to the moment it disintegrated it took about 14 seconds then we try it with the lower concentration drain cleaner and we also time this for this lower concentration run it took about 20 seconds so almost 50% longer so in conclusion there's two major methods to clean up sulfuric acid and I think the distillation method is superior its superior in purity and also safety because we're not going to be pumping sulfuric acid into the air also apparently the peroxide might not be required at least for the drain cleaner that I used okay so that's it for now and I'll see you on the next one again here's a list of the videos that I'm currently editing and future videos I plan to film in the videos being edited category you can vote for the one that you want me to publish next and in the future video category you can vote for the one that you want me to film next also if you're feeling generous please donate to my patreon account because with a bigger budget per video I can do more things also instead of stockpiling videos I've decided I'm going to publish them as soon as I added them so in the next month or so there's going to be a lot of videos coming out on my patreon I also added a milestone and if we get to $250 per video I'll commit to doing videos for at least six months

Channel: NileRed

Views: 1,125,959

Rating: 4.9143224 out of 5

Keywords: sulfuric, acid, clean, how, to, nile, red, h2o2, peroxide, method, distillation, drain, cleaner, distill, science, chemistry, nilered, pure, purify

Id: 4DUGRWjdNLI

Length: 19min 0sec (1140 seconds)

Published: Sun Jan 17 2016

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