Laboratory Materials - Video Tutorials & Practice Problems

Laboratory Materials 1

Hey everyone. So in this video, we're gonna take a look at some instruments that you're going to eventually see within your typical chemistry laboratory. Now, remember the laboratory is just a way of us taking what we're learning within lecture and applying it in real life through experimentation. Now, let's take a look at some of these apparatuses. And what's important here is to be able to identify the apparatus and what is its primary use. Right. So for the first one, we have what's called a transfer pipette. These transfer pipettes are usually made up of basic or cheap types of plastic. And the whole point of it is within a name to transfer small amounts of liquid for the next one to the right of it. We have what is called a bure it now in this bureau, you pour in your liquid in here. Um, sometimes it's liquid is called a tie Trent. And let's say that it measures here to 25 MS. And let's say, I open up this stop cock here and I let the water go down. So it's dripping out. And let's say it goes and we stop it at 18 mls, we would say 25 minus 18 would say that seven mls have been delivered under the use of this pure it. So what's the whole point in use of of your IT? Well, one predominant use of it is to help prepare solutions and a second use for it. What you're going to eventually do if you haven't already is for acid based iterations. Next we have a funnel here. This one is in particular called a Buckner funnel and typically there's holes within this but no funnel here. And what we do is we place a filter paper on top of it. So basically it's predominant use is for filtration, where we separate solids from liquids. Okay, the liquid portion will go through the holes and down here and what's left behind. These are solid particles. Alright, next year we have is a vacuum flask. It's a vacuum flask because it has this little attachment here which you can connect the hose to and sometimes we'll use the Buckner funnel with this volume on volume flask. We place the Buckner funnel here and we touched the, basically the tube, the tubing right there. We turn on the vacuum suction, it would help the water to come down faster and it basically aids the filtration of the Buckner funnel. Next what we have here is just a typical graduated cylinder. So what's the whole point of a graduated cylinder. It's just to measure volume. So measure out volumes. The thing with this one is, it's not as precise. So you're just trying to transfer a certain amount. You don't care too much about precision. You're just trying to move a good amount of liquid Here. This next one is a beaker. These beakers can come pretty large, it can go from 250 mls or 500 mls as the typical sizes. Now there are sizes that range outside of these outside of this range, but typically you'll see 2 50 to 500 within your laboratory. And here this is just to measure out larger quantities of water or larger quantities of liquid. Next we have what's called a volumetric flask. Now what's the whole point of volumetric flask? We use them for dilutions. So let's say that we have 10 mls of 0.20 Moller or some type of solution. Alright, so we placed that in here and all we do is we fill up the rest with water up to this line and then we would invert it and mix it thoroughly in order to dilute that previous solution. So here a volumetric flask, it just helps us to dilute our initial solution or a concentrated solution. These can range in different sizes. Some can even go up as high as one leader. Um You may not see that within your laboratory but realize that is possible. And then finally here what we have is an early Meyer flask. What what is this predominant use, it's just to help us transfer large amounts of solutions. So some of these are typical types of instruments you'll come into contact with within your chemistry laboratory. So just familiarize yourself with the the image the name and their predominant use

Laboratory Materials 2

here, we're gonna say, we're gonna continue with the discussion, we're still gonna look at solutions and the transferring of them were also going to pay closer attention to solids and their use and instruments needed for them within the chemistry laboratory. So in the first image, what we have here is we have what's called a crucible, which is the container and its lead. Now within your basic chemistry laboratory we have these large ovens. These ovens can reach temperatures in the several hundreds of degrees. Basically what we do here is we take our wet sample and we place it in the oven usually wait until the next following lab until it's completely dried out. So here are crucible, we're gonna say is used to heat small amounts right of solid material at high temperatures. Now we're gonna say here that when our substance is wet, we're gonna say that it's hydrated and once you put it in the crucible and then place that within the oven and give it enough time, it'll dry out all the water will be driven out of the out of the substance. And what we'll have left is something that is completely dry. And when we say that a substance is completely dry, we call it anhydrous. Okay, so this would be our dry sample and this is when it's wet. Now, similar to a crucible is we have here an evaporating dish or an evaporation dish. In this case we don't use an oven in order to heat our our hydrated substance. What we do here is we just place some liquid on this dish and give it time to evaporate, leaving behind a solid. So this here is just used two contain a small amount of liquid um so that it can undergo evaporation, It undergoes evaporation. And remember the whole point of this is to leave behind a solid. Now the next two objects here we have our spatulas and here we're gonna say that this is a scoop up so spatulas when we're trying to take a small amount of powdered solid um from a container within your lab and maybe place it within a beaker or a flask. So this just helps us to transfer small amounts mhm of solid, usually in powdered form. And as scuba lies just to help us to transfer larger amounts of solid. Next what we have here is our basic funnel. Remember we've seen a Buckner funnel earlier, which is used in vacuum filtration here. This is just a regular funnel. Now, it's primary uses. So basically it helps us to transfer liquids or solids if they're in powdered form or or small enough um into a container with a small opening. Mhm. Right, so in this case, all it's helping us to do is stop spillage because it's hard to transfer a liquid from a bottle into a flask with a small opening. So we use a funnel to help us, we just poured into the funnel and we make sure that as much of it as possible, gets within that flask. Another method that we can have with this is if we use filter paper. Okay, so within lab they'll teach you how to fold a filter a piece of filter paper. So basically your filter paper is circular like this. And what you do is first you fold it in half and then you'd fold that half and half as well. Okay, so you have that and then you would hold it out like this and just put your hand through it and open it up and it would form basically like a porous membrane and you place that within the funnel and then you can pour a liquid through there. And what would happen here is the liquid portion would drip out of the filter paper into the flask. And what will be left behind would be some solid that's solid sometimes refer to it as a residue. So if filter paper is used it can be used mhm. Two separate a liquid which is our Phil trait and a solid which is our residue. Now, finally, what we have here our last image. This is also a funnel but it's different from a Buckner funnel which is typically used for vacuum filtration. It's different from a regular funnel which is used for simple filtration or just the transferring of liquids or solids into a container with a smaller opening. This is a separate story funnel or separating funnel and the whole purpose of this separate story funnel. It basically helps us to see. It helps with the separation of a liquid and a solid by exposing the solid to another solvent. We tend to call this partitioning and we'll talk about this later on. We typically see this when we're doing acid base extractions, so we'll talk in greater detail about what exactly is an acid base extraction and how exactly is the secretary funnel use when doing this type of process. So these cover a majority of the basic instruments that you should be exposed to at some point within a chemistry lab. So it's important to know what they look like and their main purpose. Again, laboratories are a lot of work. I know and you don't get as many credits for it. Um but it is taking into practice some of the concepts you're learning in class and bringing them into a real world, real world setting. So just follow what your professor says or your ta says within the lab. Always be careful when transferring of any liquids or solutions. Follow all the rules study. You should be able to do well within your lab

Laboratory Materials

if a scientist wishes to measure out exactly 25 mls of a 250.100 molar hydrochloric acid solution and add added to a 0. moller sodium hydroxide solution. Which instrument would be most useful. So here we have an image of an extractor. So let's just start out with that. And one of our options is a sucks let extractor. Now this is just a type of unique extractor. So the name doesn't really matter. What's important here is that we need to be very precise with our measurements because we need to figure out exactly 25 MS. An extractor is just basically used within distillation here. This is not a distillation process here. We're trying to create a solution by being as precise as possible with our measurements and extracted. Wouldn't be good for that. A transfer pipette is just a way of moving a small amount of liquid very quickly. Not precisely. So, option A wouldn't work here. A graduated cylinder helps us to move large amounts of liquid. But again, it's not precise. It doesn't give us an exact exact measurements we need here a volumetric flask that's typically used for dilutions And here we're not trying to create a dilution. We're not having our solution and adding water to it in this question. We're dealing with hydrochloric acid and sodium hydroxide. So we're dealing with an acid based hydration of your right is the answer because if you're right is great for helping us create solutions. And it's also really good in helping us with acid based hydration, which is what this question is alluding to. And because of that, again, option E of the bure, it is the correct answer.

Laboratory Materials

What is the polarity of a solution made by mixing 200 miles off pure water with 100 miles off 1000.75 Mueller Potassium chloride solution. All right, so any time we're adding water to any type of solution, that means that we are doing a dilution. Remember, a dilution. Okay, Is any time we're adding mixing or tight trading with water. And when it comes to dilution, we use the dilution formula, which is m one V one equals m two V two. So they're asking us what is the polarity after? We've added this water. So they're asking me what is m two? The word off means multiply, Which makes sense because this would be my M one. This would be my V one. They're multiplying each other. We don't know what M two is now. The two equals our final volume. Yes, and our final volume equals the volume Initially, that we had plus the volume of added water. So initially we started out with 100 m. Els right here, 100 miles. And what did we do to that 100? Emil's, while we added on additional 200 miles of water so that mean my final volume or V two is 300 NL's. So we have to do now is solved for em, too. So divide both sides by 300 miles. Yes, so we'll just be 0.75 divided by three. So my new polarity would be 0.25 Moeller giving the option B as the correct choice. So remember, in a dilution, your new concentration normal clarity, which is M two, is always smaller than your M one. So this is just a basic dilution question. What? We have to use the dilution formula continuing with this idea of dilutions. Let's if you guys can figure out how to answer. Example three. Once again, if you get stuck and don't know where to go, just come back and take a look at the next example video where I go over how to approach this very question

Laboratory Materials

So for a final example question on this page, we're gonna deal with a dilution. Now, it's one thing to just use the dilution equation to solve within the classroom. But it's another thing when you're in the lab and asked to do a dilution yourself, the illusions could be a bit tricky. So the approach we wanna take is this. So we want to create 100 fold dilution. Okay, so just remember, in a dilution that means that are solvent will have to be larger than our solution. Okay, so we have to put that out there first. So knowing this, we know that they won't work because in a the solvent is less than our solution. So that's not gonna work. And when it comes to a dilution where they want us to do 100 fold dilution, so that means it's gonna be a ratio of 100 to 1. Well, what exactly is the 100 referring to? And what exactly is the one referring to when it comes to a dilution we're gonna say Here it is the solvent plus solution and it's ratio to the amount of solution. Okay, so that's what the 100 toe one is referring to 100 fold. Dilution is 100 to 1. Maybe we have ah 100 when it comes to adding up the amount of solvent and solution together compared to one for the solution. So here we know that a is out. So if we take a look at the other options, what do we have for B? We have 90 and 10 So this would be plus 10 and then this would be 10th. So that would total up to 100 to 10. And this would represent a If you divide both by 10 this would represent a 10 to dilution or a tenfold dilution, which is not what we want next for See, we have 99 parts solvent plus one part solution solution. So that would be 99 plus one and then one. So that would be 100 to 1. This would represent our 100 fold dilution If we take a look at the last ones here we have 100 plus one toe, one that be 101 toe one. Not quite what we want. This would be 101 full dilution which is not what we want. And then the last one would be 10 plus one toe one, so that would be 11 to 1. So this would be an 11 fold dilution. So here, just remember a dilution. When it comes to the ratio, it's the amount of solvent plus solution in ratio to the amount of solution. Hundredfold would mean that we have 100 when it comes to the amount of solvent and solution together compared to the just the amount of the solution.