Laboratory Materials - Online Tutor, Practice Problems & Exam Prep

In a chemistry laboratory, various instruments are essential for experiments. A transfer pipette is used for transferring small liquid amounts, while a burette measures precise liquid volumes, often for titrations. Graduated cylinders and beakers measure larger volumes. For solids, crucibles heat materials at high temperatures, and evaporating dishes facilitate evaporation to leave solids behind. Funnels assist in transferring liquids and solids, with filter paper used for separation. Understanding these tools enhances practical application of concepts like acid-base reactions and solution preparation.

Laboratory Materials 1

Hey everyone. So in this video, we're going to 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 for us to take what we're learning in lecture and apply it in real life through experimentation. Now let's take a look at some of these apparatuses. What's important here is to be able to identify the apparatus and what its primary use is. 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 burette. Now in this burette, you pour 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 use the equation 25 minus 18 and say that 7 ml's have been delivered through the use of this burette. So, what's the whole point and 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 Büchner 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. The liquid portion will go through the holes and down here, and what's left behind is our solid particles.

Next, we have a vacuum flask. It's a vacuum flask because it has this little attachment here, which you can connect a hose to. And sometimes we'll use the Büchner funnel with this vacuum flask. We place the Büchner funnel here, and we attach the tube 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 Büchner 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 a 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 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 is its predominant use? It's just to help us transfer large amounts of solutions. These are some typical types of instruments you'll come into contact with within your chemistry laboratory. So just familiarize yourself with the image, the name, and their predominant use.

Laboratory Materials 2

We're going to say we're going to continue with the discussion. We're still going to look at solutions and the transferring of them. 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 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. 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 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 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, 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 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 dealing with 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 setting. So just follow what your professor says or your TA says within the lab. Always be careful when transferring 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? Here we have an image of an extractor. Let's start out with that, and one of our options is a Soxhlet extractor. 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 basically used within distillation. Here, this is not a distillation process. 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. 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 is typically used for dilutions and here we're not trying to create a dilution. We're not diluting 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, the burette, is the correct answer.

Laboratory Materials

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 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 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 0.25 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 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.

Laboratory Materials

So for our final example question on this page, we're going to deal with a dilution. Now, it's one thing to 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. The approach we want to take is to create a 100-fold dilution. Just remember, in a dilution, that means that our solvent has to be larger than our solution. So knowing this, we know that option a won't work because in a, the solvent is less than the solution. And when it comes to a dilution, they want us to achieve a 100-fold dilution. That means it's going to be a ratio of 100 to 1. But what exactly is the 100 referring to, and what exactly is the 1 referring to? In a dilution, we're going to say here it is the total of solvent and solution. That's what 100:1 is referring to. A 100-fold dilution is 100:1, meaning we have 100 parts total of solvent and solution together compared to 1 part of the solution. So here we know that a is out.

If we take a look at the other options, for b, we have 90 parts solvent + 10 parts solution. That’d be 90+10, which totals up to 100, and then 10 for the solution alone. If you divide both by 10, this would represent a 10:1 dilution, or a 10-fold dilution, which is not what we want. Next, for c, we have 99 parts solvent + 1 part solution. That'd be 99+1, summing to 100, and then 1 for the solution alone. This would represent our 100-fold dilution.

Looking at the last options, here we have 100 parts solvent to 1 part solution, summing to 101. This would be a 101:1 ratio, not quite what we want. This would be a 101-fold dilution, which is not what we seek. Lastly, we have an option with 10 parts solvent + 1 part solution, totaling 11. That'd be 11 to 1, representing an 11-fold dilution. So, just remember, in a 100-fold dilution, we have 100 parts of the combined solvent and solution compared to just the amount of the solution alone.

Here’s what students ask on this topic:

What is the primary use of a burette in a chemistry laboratory?

A burette is primarily used for measuring precise volumes of liquids, especially in titrations. It allows for the controlled addition of a liquid, known as the titrant, to another solution. By reading the initial and final volumes on the burette, you can determine the exact amount of liquid dispensed. This precision is crucial for experiments that require accurate measurements, such as acid-base titrations, where the endpoint of the reaction needs to be determined accurately.

How does a vacuum flask aid in filtration in a chemistry lab?

A vacuum flask, also known as a Büchner flask, aids in filtration by creating a vacuum that speeds up the filtration process. When connected to a vacuum pump, the reduced pressure inside the flask helps draw the liquid through the filter paper placed in a Büchner funnel. This setup is particularly useful for separating solids from liquids more efficiently than gravity filtration alone, making it ideal for experiments requiring quick and effective filtration.

What is the difference between a crucible and an evaporating dish?

A crucible is a container used to heat small amounts of solid material at high temperatures, often in an oven or over a flame. It is designed to withstand very high temperatures and is used to drive off water or other volatile substances, leaving behind an anhydrous solid. An evaporating dish, on the other hand, is used to evaporate liquids at lower temperatures, typically at room temperature or with gentle heating. The goal is to leave behind a solid residue after the liquid has evaporated.

What is the purpose of a volumetric flask in solution preparation?

A volumetric flask is used for preparing precise dilutions and standard solutions. It is designed to contain a specific volume of liquid when filled to the calibration mark on its neck. To prepare a solution, you add a measured amount of solute to the flask, then add solvent up to the calibration mark. The flask is then inverted and mixed thoroughly to ensure a uniform solution. This precision is essential for experiments requiring accurate concentrations of solutions.

How is a separatory funnel used in a chemistry lab?

A separatory funnel is used to separate immiscible liquids or to perform liquid-liquid extractions. It allows for the partitioning of compounds between two solvents based on their solubility. The funnel has a stopcock at the bottom to control the release of the lower layer. By shaking the funnel and allowing the layers to separate, you can drain the denser liquid from the bottom, leaving the less dense liquid in the funnel. This technique is commonly used in acid-base extractions and other separation processes.