Laboratory Materials - Video Tutorials & Practice Problems
Get help from an AI Tutor
Ask a question to get started.
The laboratory portion of your chemistry course puts into practice some of the concepts you’ll gradually be learning. In this section we will familiarize ourselves with some of the basic apparatuses you’ll be using.
Laboratory Materials
1
concept
Laboratory Materials 1
Video duration:
11m
Play a video:
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. Alright. 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 burette. Now in this burette you pour in your liquid in here, sometimes this liquid is called a titrant. And let's say that it measures here to 25 ml, and let's say I open up this stopcock 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 ml's. We would say 25 minuteus 18 we'd say that 7 ml's have been delivered through the use of this burette. So what's the whole point in use of a burette? 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 titrations. Next, we have a funnel. Here this one is in particular called a Buckner funnel. And typically there's holes within this button or funnel here and what we do is we place a filter paper on top of it. So basically its predominant use is for filtration where we separate solids from liquids. K? The liquid portion will go through the holes and down here, and what's left behind is our solid particles. Alright. Next here, 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, volume flask. We place the buckner funnel here and we attach 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. They can go from 250 ml or 500 ml as the typical sizes. Now there are sizes that range outside of these, outside of this range, but typically you'll see 250 to 500 within your laboratory. And here this is just to measure out larger quantities of water, or larger quantities of a 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 ml's of 0.20 molar of some type of solution. Right? So we place that in here, and then what 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 concentrated solution. These can range in different sizes, some can even go up as high as 1 liter. You may not see that within your laboratory, but realize that it's possible. And then finally here, what we have is an Erlenmeyer Flask. What what is its 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.
2
concept
Laboratory Materials 2
Video duration:
8m
Play a video:
We're gonna say we're gonna continue with the discussion. We're still gonna look at solutions and the transferring of them. We're also gonna pay a 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 lid. 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, our crucible, we're gonna say, is used to heat small amounts 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 to contain a small amount of liquid, 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 are spatulas, And here we're gonna say that this is a scupula. So, a spatula is when we're trying to take a small amount of powdered solid, from a container within your lab and maybe place it within a a beaker or a flask. So this just helps us to transfer small amounts of solid, usually in powdered form. And a scupola is just to help us to transfer larger amounts of solid. Next, what we have here is a basic funnel. Now remember, we've seen a Buckner funnel earlier, which is used in vacuum filtration. Here, this is just a regular funnel. Now its primary uses so, basically, it helps us to, transfer liquids or solids if they're in powdered form or or small enough, into a container with a small opening. 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 pour it 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. 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 in half as well. 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 would 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 solid sometimes we refer to it as a residue. So if filter paper is used, it can be used to separate a liquid, which is our filtrate, 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 separatory funnel or separating funnel. And the whole purpose of this separatory funnel, it basically helps us to it's this 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 deal doing, acid base extractions. So we'll talk in greater detail about what exactly is an acid base extraction and how exactly is a separatory funnel used 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. But it is taking into practice some 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.
3
example
Laboratory Materials
Video duration:
3m
Play a video:
If a scientist wishes to measure out exactly 25 ml of a 0.100 molar hydrochloric acid solution and add it to a 0.200 molar 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 suxlet 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 ml. 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. An extractor 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 the 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 titration. A burette is the answer because a burette is great for helping us create solutions and it's also really good in helping us with acid based titrations, which is what this question is alluding to. And because of that, again, option e of the burette is the correct answer.
4
example
Laboratory Materials
Video duration:
2m
Play a video:
What is the molarity of a solution made by mixing 200 ml of pure water with 100 ml of 0.75 molar chloride solution. Alright. So anytime we are adding water to any type of solution, that means that we are doing a dilution. So remember, a dilution is anytime we're adding, mixing, or titrating with water. And when it comes to dilution, we use the dilution formula, which is m 1v1 equals m 2v2. So they're asking us what is the molarity after we've added this water? So they're asking me what is m2. The word of 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 m2 is. Now v2 equals our final volume. And our final volume equals the volume initially that we had plus the volume of added water. So initially we started out with 100 ml's right here, 100 ml's. And what did we do to that 100 ml? Well we added an additional 200 ml of water. So that means my final volume or V2 is 300 ml. So all we have to do now is solve for m2. So divide both sides by 300 ml's. So it would just be 0.75 divided by 3. So my new molarity would be 0 point 25 Molar. Giving me option B as the correct choice. So remember, in a dilution your new concentration or molarity, which is m two, is always smaller than your m one. So this is just a basic dilution question where we have to use the dilution formula. Continuing with this idea of dilutions, let's see if you guys can figure out how to answer example 3. 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.
5
example
Laboratory Materials
Video duration:
2m
Play a video:
So for our 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 a classroom, but it's another thing when you're in the lab and asked to do a dilution yourself. Dilutions can be a bit tricky. So the approach we wanna take is this. So we wanna create a 100 fold dilution. K. So just remember in a dilution, that means that our solvent will have to be larger than our solution. K. So we have to put that out there first. So knowing this, we know that a 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, here they want us to do a 100 full dilution. So that means it's gonna be a ratio of a 100 to 1. But 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+olution. Solution. That's what the 100:1 is referring to. A 100 fold dilution is a 100:1, meaning we have 100 when it comes to adding up the amount of solvent and solution together compared to 1 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 9010. So this would be 90 plus 10 and then this would be 10. 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 1 dilution or a 10 fold dilution, dilution, which is not what we want. Next, for c, we have 99 parts solvent plus plus 1 part solution. So that'd be 99 +1, and then 1. So that'd be a 100 to 1. This would represent our 100 fold dilution. If we take a look at the last ones, here we have a 100 plus one to 1. So that would be 101 to 1. Not quite what we want. This would be a 101 full dilution which is not what we want. And then the last one would be 10+1. So So that'd be 11 to 1. So this would be an 11 fold dilution. So here just remember solution. 100 fold would mean that we have a 100 when it comes to the amount of solvent and solution together compared to the just amount of the solution.
Do you want more practice?
We have more practice problems on Laboratory Materials