Laboratory Materials - Online Tutor, Practice Problems & Exam Prep

Laboratory Materials 1

Hey everyone. So in this video, we're going to take a look at some instruments that are 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.

All right, so for the first one we have what's called a transfer pipette. These transfer pipettes are usually made U 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 Bureau 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 stop here and I let the water go down South, it's dripping out And let's say it goes and we stop it at 18 mL, we would say 25 - 18 would say that 7 mL have been delivered after 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. It's for acid base titrations. Next we have a funnel here. This one is in particular called a Buckner funnel and typically there's holes within this 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, OK. The liquid portion will go through the holes and down here and what's left behind is our solid particles.

All right, 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 on 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 I'll 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 mL or 500 mL as the typical size is. 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 a 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 old point of volumetric flask? We use them for dilutions, so let's say that we have 10 mL of 20 molar or 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 is 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 liter. You may not see that within your laboratory, but realize that is possible. And then finally here what we have is an Erlenmeyer flask. What what is this predominant use? It's just to help us transfer large amounts of solutions. OK, 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 going to say we're going to continue with our discussion. We're still going to look at solutions and the transferring of them, but we're 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 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 going to say, is used to heat small amounts of solid material at high temperatures. Now we're going to say here that when our substance is wet, we're going to 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 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, OK. 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 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 going to say that this is a Scoopula. 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 beaker or a flask. So this just helps us to transfer small amounts of solid usually in powdered form and a Scoopula is just to help us to transfer larger amounts of solid.

Next what we have here is our 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 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 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's 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 a 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 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 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 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 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 suck select 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-base 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-base titrations, which is what this question is alluding to. And because of that, again, option E of the burette is the correct answer.

Laboratory Materials

What is the molarity of a solution made by mixing 200 mills of pure water with 100 MLS of 0.75 molar potassium chloride solution? All right, so anytime we're 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 M1V1=M2V2.

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 M1. This would be my V1. 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 MLS right here, 100 MLS. And what did we do to that 100 MLS? Well we added an additional 200 MLS of water so that mean my final volume or V2 is 300 MLS. So all we have to do now is solve for M2 so divide both sides by 300 mills so it would just be oh .75 / 3. So my new molarity would be .25 molar, giving me option B as the correct choice.

So remember in a dilution, your new concentration or molarity which is M2 is always smaller than your M1. So this is just a basic dilution question where we have to use the dilution formula. Continuing with this idea of dilution, let's see 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 going to 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 want to take is this. So we want to create a hundred fold dilution, OK. So just remember, in a dilution that means that our solvent will have to be larger than our solution. 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 going to work. And when it comes to a dilution, hey they want us to do 100 fold dilution. So that means it's going to be a ratio of 100 to one. But what exactly is the 100 referring to? And what exactly is the one referring to when it comes to a dilution? We're going to say here it is the solvent plus solution and its ratio to the amount of solution. OK, so that's what the 100 to one is referring to.

100 fold dilution is 100 to 1, meaning we have 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 90 + 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 12:50 dilution or A10 fold dilution which is not what we want.

Next for C we have 99 parts solvent plus one part solution solution so that would be 99 + 1 and then one, so that'd be 100 to one. This would represent our hundred fold dilution. If we take a look at the last ones here, we have 100 + 1 to 1 that be one-on-one to 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 + 1 to 1, so that'd 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. 100 fold 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.