Separating Techniques: Simple Distillation

[Music] so our next method of separating technique is our simple distillation and simple distillation can be used to separate a solvent from a solution so this is and we're actually using the same solution copper sulfate solution in some ways it's similar to evaporation and crystallization but the problem with those two methods is that when we heated the solution in an open container so either our salt solution or our copper sulfate solution the problem was that we lost our solvent in both cases water because we heated them in an open container an evaporating basin and the water just simply evaporated off as a gas and would have then mixed with the air so we lost the solvent as such so what we can use this simple distillation to do is to separate our solution and what we'll get at the end is our solute but we can also collect our solvent and so we'll be left with our solute in the round bottom flask and we will collect our solvent our water in this case in our flask here and so that's what we use simple distillation for so this is the apparatus set up you can see that it's quite complicated and there's lots of different parts to it but i'll talk through those parts as we go along first thing i want to talk you through is this and this condenser it's sometimes called a liebig condenser and essentially what that will do is that will kill our gas during the experiment so essentially what we'll do is we'll start heating the solution in our round bottom flask here the water will evaporate just as it did with evaporation but what will happen is it will pass through this tube into the condenser and when it gets to the condenser what it will do is it will cool down why does the gas kill down well what we have in this condenser is actually two tubes there's an inner tube where our gas will pass through but then there's also an outer chip around that think of almost like a toilet roll inside a kitchen roll and so the toilet roll is smaller so there'll be a bit of space around the toilet roll and surrounded by the kitchen room if that makes sense and essentially in that gap is running some cold water and so you can see these and these tubes are connected one is connected to the water tap here we always put water in at the bottom and then it's pushed up the condenser and it will come out the top and remember this is in the outer chipping so it's not actually mixing with the gas that passes through the inner tubing so i'll show you what happens here they got the water is not flowing at the minute you can see if i hold the tap up there's nothing flowing out but if i turn the tap on we don't want it too strong but have a look at the condenser see if you can see the water starting to to flow through okay so what is happening now it's hard to see because water is a colorless liquid but what is happening now is water is entering the condenser here it's flowing around this outer chipping so around the outside of the condenser and then it's coming out here and coming through this delivery tube and out here so you can see there's no water actually flowing through the inner chip it's all around that idler tube and if i hold that it's very very cold so what is going to happen is our water will evaporate the gas passes through into the condenser and then it is cooled down because of that cold water flowing around the outside it's essentially just providing a really cool surface a bit like um in the mornings in the winter where you see condensation on the window because the water vapor from the air is cooling down on the cool surface and condensing into a liquid so we'll see that when we get our distillation going so i'll just turn that on a little bit more we don't want that on too much though so let me flip around now to the start of our experiment and the start of the apparatus so what we've got here is what we call a round bottom flask literally it's a flask that has a round bottom and what we're going to do is we're going to heat the solution inside the solution we've got in here is copper sulfate solution we could also use solutions like our salty water and that would allow us to collect the salt and also the pure water and this is a way of collecting pure water and for example on cruise ships and where they would take water from the sea and and they can use distillation and to actually get pure water that means water with nothing else dissolved in it and this is something we can use for that now inside the flask might be hard for you to see but we have a few little small white solid granules and these are called anti-bumping granules and essentially they are little solid particles that don't dissolve in our solution so they don't affect the composition of the solution as such but what they do is they um the exam references they promote smooth boiling they essentially make sure that this doesn't bubble up too much and so this the boiling will be nice and smooth we'll get nice small bubbles in our solution rather than it kind of bumping around as such and splashing around our flask because we don't want too much splashing in this flask and we certainly don't want any liquid splashing up into our condenser we want that just to be our pure um gas which will be steam as such okay so that's anti-bumping granules and we say that they promote smooth boiling so let's get this process going to get this process going i need to heat my solution so let me turn on my bunsen burner there we go and again we don't heat it too strongly because it is a solution that is a liquid as such and so we don't want to put on the roaring flame and but we'll put it roughly on the half open and half closed flame and heat this gently okay so this is going to heat the solution and what will happen as with evaporation it will cause the water to evaporate but um the solute which in this case is our copper sulfate will not evaporate it will not melt and or evaporate because it's melting point and boiling point is a lot higher so it will leave the copper sulfate particles behind so that's starting to heat nine other parts of the evaporation of the sorry distillation apparatus is a thermometer here and you'll see the bulb of the thermometer is just at this junction and before it goes into the condenser because what we want to do is we want to measure the temperature of the gas as it passes into the condenser and that can allow us to identify the gas as such and so water for example has a boiling point of 100 degrees c so what we should see is that when we see the gas starting to pass in the into the condenser the um temperature on the thermometer should be a hundred degrees c as that gas passes across it so we don't have any water evaporating just yet but the temperature on the thermometer is increasing so it's about 35 at the minute i'll maybe open this up slightly more to get it to go in a little bit quicker you can start to see a little bit of condensation at the top of the round bottom flask which means some gas is starting to evaporate and and then but it's cooled down just at this stage what we want it um at is the point where the gas is going to actually pass up and into the condenser okay so what you can see now we've left this running for a minute or two and we can see that our solution is starting to boil and so you can see that with the bubbles that are forming and what is happening is our water is evaporating you can see the temperature on the thermometer and is a hundred it's maybe 101 degrees but um it's very very close to 100 which tells us that the gas that is passing our thermometer bulb is at 100 degrees c and what we can see now in the condenser is that the gas has actually passed through into the condenser and you can see that with the steam here but what's happening is you can see some water actually flowing through at this end so it's a gas really up here but as it cools it will condense and form a liquid that's the change of state from gas to liquid is um is condensing and you can see the water flowing through and it's being collected in the flask here and what you can see is that the liquid that we're collecting is colorless and that tells us that it is pure water so there's no more copper sulfate dissolved in it if there was any copper sulfate dissolved in it it would be blue but you can see it's a nice colorless liquid and that is pure water so that is water with nothing else dissolved in it it's a pure substance and essentially we just keep this process going until the solution in the round bottom flask has totally um disappeared and what we will be left with is just our copper sulfate solute and that is no longer dissolved in the solution so again um solution is heated water evaporates and forms a gas steam the stain passes through into the condenser where it is cooled down why is it cooled down because it's got cold water running around the outside so if i touch that it's very very cold because of the cold water running around the outside and that is being pushed in at the bottom and is flowing out at the top and so the gas condenses and forms a liquid and that liquid is collected in the flask here so our distillation process is now finished we can see that no more liquid is being collected in our flask here there's no more liquid dropping going and if you have a look at the round bottom flask what we're left with is and hopefully you can see in there at the bottom we have some blue powder which is our copper sulfate and anything that is blue is hydrated so it still contains some water bonded to it but it's no longer a solution it is a solid but you can hopefully see on the outside as well we've got some white powder and that is anhydrous copper sulfate so that is copper sulfate where the water molecules have been totally removed and it would be white which we'll see later and is our chemical test for water so anhydrous copper sulfate is white but the hydrated is blue and but the point of this separating technique was to separate the solvent from the solution so you can see this is a method where we use evaporation followed by condensation to collect our solvent which is in this flask but we also have been able to collect our solute or keep our solute in our round bottom flask so that's the method of simple distillation [Music]

Channel: C Armstrong

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Id: wuf235-7oK8

Length: 11min 25sec (685 seconds)

Published: Mon May 09 2022