If we are going to learn how to do
chemistry, the first thing we need to do is learn a little bit about all of the equipment
in the laboratory. We are probably familiar with the way that chemistry labs are portrayed in
movies, cartoons, and horrible stock images, but not surprisingly a real chemistry lab does
not look very much like this. Instead, a chemistry laboratory will typically look something like
this. So let’s familiarize ourselves with the instruments we will be using on a regular basis.
First off, if we are going to do chemistry we are going to have to use lots of glassware. Let’s
start with one of the more familiar items. These are beakers. There is a range of beaker sizes
available, ranging from as small as 5 milliliters, to as large as several liters, and there are
different situations in which these different sizes would be desirable. Most often, we tend to
use beakers between around 10 to 400 milliliters. Beakers have many uses. Reactions can be conducted
in them. They can be used to transport solutions and solvents. Or they can be used as water
baths, meaning we can suspend some other vessel in the beaker in order to control its temperature.
Always be aware of what you are using a beaker for and use the appropriately sized beaker for the
job. The measurements on the sides are great for estimating the volume, but we do not carry
out actual measurements of volume using beakers, we have glassware that is more accurate
for measuring volumes when necessary. Speaking of measuring volumes, next up we have
the graduated cylinder. A graduated cylinder is used to measure the volume of a liquid.
These also range quite a bit in size. Be aware that they are tall, so you may at some point
accidently knock one over. In order to avoid this, always place them down where you can see them or
where less movement is occurring. We should also be aware that when taking measurements with a
graduated cylinder, we will always read from the bottom of this concave meniscus. This word
refers to the way the liquid climbs a little bit up the edges, and to avoid ambiguity, we
will take readings from this position here. Next we have test tubes, test tube racks, and test
tube holders. A test tube is a very small reaction vessel, which is nice to use when observing
obvious visible changes in the reaction. They don’t stand up by themselves so be sure to place
them a test tube rack so they don’t roll away. A test tube holder, like this one, can
be used to hold a test tube above the flame of a Bunsen burner, or suspend it in
a water bath. Get comfortable holding one of these before heating it and be sure to have one
that fits the size of test tube you are using. Next let’s check out another recognizable piece
of glassware, the Erlenmeyer flask. A conical, or Erlenmeyer flask looks like this. These are
typically used for mixing reagents together and conducting a reaction. Again, they come in
various sizes, and the measurements on the sides are quite imprecise, so they shouldn’t
be used when accuracy is necessary. The tapered edges leading to the small opening at
the top prevent spilling, and they also make these flasks ideal for clamping, which is something we
will commonly want to do. If the mixture needs to be manually stirred, you can manipulate
them with less fear of the solution escaping which is why these are typically preferred
for running reactions over beakers. Next we have the indispensable Buchner flask,
or filter flask. These are very similar to the Erlenmeyer flask, it is simply that the Buchner
flask has a side arm which is used when conducting vacuum filtration, which we will discuss in
another tutorial. Avoid using these for anything other than filtrations as the side arm
opening can cause the liquid to escape. With the Buchner flask covered, let’s check
out the Buchner funnel and accompanying rubber adaptor. The Buchner funnel is also
used when conducting vacuum filtrations. These sit in the Buchner flask and are
typically made of ceramic, but plastic ones are sometimes used. For a better seal, we
tend to use the rubber adaptor. These aren’t all that stable so be sure to clamp the flask
first before assembling the filtration setup. Next let’s examine the filter funnel. For
gravity filtrations, we use this kind of funnel. Either cotton wool or a folded piece of filter
paper can be used for gravity filtrations, which will also be properly demonstrated later. To finish off the funnels, let’s check out the
powder funnel. When wanting to add powder to a flask, which could be a drying agent, or any
solid reagent, sometimes it is much easier to use a powder funnel.These can be placed on top
of a flask, and a solid can be added easily. These typically are not made of glass so they are
easily distinguishable from the other funnels. Be sure to check and see if it is clean
before using it and clean it afterwards. Next we have the spatula. When picking up
solids, we will use a spatula. Some are curved, some are flat, and they usually bend if
necessary, but be gentle whenever possible. Similarly we have the stirring rod.
When wanting to briefly stir something, a stirring rod is the best option. Do not get this
confused with a thermometer, and be careful when putting these down as they do roll away.
Then we get to the pipette. For adding small amounts of liquid, we use
a pipette. Using a pipette bulb, a liquid can be taken up and put somewhere
else. Simply squeeze, place into the liquid, release the bulb to draw the liquid into the
pipette, and then transfer it to the new vessel. Next up we have the burette. These are commonly
used with titrations. Like a graduated cylinder, it has these gradations for measuring volume, but
unlike a graduated cylinder they are inverted, so that you can measure how much volume
is being added to some other vessel. A more thorough demonstration of this instrument
will be shown when we conduct a titration. Then there is the volumetric flask. When making
standard solutions, we use a volumetric flask. Much like the volumetric pipette, a single line
indicates the exact volume of this flask. Because of the long necks, these can be knocked over, so
like the graduated cylinders, be careful where you place them. Also check which cap you have, as
some fit nicely but others are deceptive. When using these to make solutions, be extra careful
once you reach the neck, as this will fill up much more rapidly than the bulb, as it is so narrow.
Moving along, we find the separatory funnel, which we learned about when going over extraction
in the organic chemistry series. For separating two immiscible liquids, we will use a separatory
funnel, sometimes abbreviated as a sep funnel. When using these, make sure you have the correct
size cap so that nothing spills when inverted. Sep funnels require a ring clamp, so make sure
that the size of your ring clamp is appropriate, as if too small the funnel will be unstable, but
if too big, it will not hold the funnel at all. We will notice that the separatory
funnel has a valve for releasing liquid. Sometimes the valve comes assembled, and sometimes
they need to be assembled. We will talk more about this apparatus when we perform an extraction.
Now this is called a dropping funnel. A dropping funnel looks very similar to a sep funnel,
but they have this separate arm and a ground glass joint. These joints become important
when conducting reactions under nitrogen or argon atmosphere with air-sensitive reagents and
products. They are used to control the addition of a liquid to a reaction, and the arm keeps the
pressure constant, so the addition is smooth and continuous. If there is no need for the ground
glass joint, a sep funnel will often suffice as a dropping funnel, but it is good to
know what this is if you come across one. Next we find the mortar and pestle. If you need
to crush up some solid material into a powder, you’d use a mortar and pestle. These are pretty
simple, you simply put the material in the mortar, and crush it with the pestle. These are usually
ceramic and quite heavy, and they are fun to use. Now we get to that ubiquitous piece of glassware
for the organic chemist, the round-bottom flask. As we will come to see, for more serious
reactions, we will use a round-bottom flask. There are many sizes, and they almost always
have at least one ground glass joint in them. The roundness allows for better
heat distribution and stirring, where the joints allow for easy fitting with other
glassware. Since they don’t stand on their own, we will use a cork ring to hold them up,
which must be of an appropriate size. If securing to a solid support, be sure to
clamp them around the ground glass joint area as this is where the glass is the toughest.
To be clear, this goes for all glassware, the ground glass joint is the thickest part and
should be the area clamped whenever possible. Moving along, this is a reflux condenser. When we
want to boil a liquid, but don’t want to lose any of the volume, we will use a reflux condenser.
These can look very different from one another, but they are all used the same way. They are
essentially a tube with a jacket, although some are just a tube, but these are less reliable. The
glass jacket is filled with water through these side arms which cools the environment in the tube,
allowing for the gas to condense and drip back into the solution. In this way, the liquid is
always boiling, but never escapes the reaction vessel. Tubes are attached to the arms here, with
water flowing in from the bottom and out the top through a separate tube. It is very important to
mention, that we must never block the top of the condenser with anything, as this will cause the
pressure to build up, which could result in an accident. A more thorough demonstration
of this apparatus will be conducted later. Here we have some clamps and a clamp stand,
something we’ve already seen a few times by now. As you have likely gathered, these are
used to hold up glassware and keep them locked in place. When using these, be careful with the
weight distribution as we don’t want the clamp stand to topple over. The base may jut out in one
direction more than another, so don’t overload one side when possible. Clamps themselves are very
adjustable with several screws, and there are a few different styles in terms of precisely how
they grip the glassware. Familiarize yourself with these as we should know what kind of clamp will
work best with a particular piece of glassware. Now here, this lovely instrument is a column. We
use these when performing column chromatography. They are essentially big, long, glass
tubes with a valve at the bottom. Some have a ground glass joint at the top, and
some have solvent reservoirs. Some have a frit at the bottom, which is a porous material,
and some don’t. We will learn how to assemble and use one of these in a later tutorial,
but for now we know what they look like. Now getting to some of the smaller accoutrements,
this is filter paper. Filter paper comes in various sizes and gradings depending on the
size of the particles you are filtering. Generally speaking, a finer grading
will filter a solution more slowly. Filter paper will be used for
the Buchner filtration setup but can also be used for gravity filtrations,
which we will perform later in the series. Filter paper can also be used to passively
dry solids as they tend to absorb liquids. Now this is a watch glass. A watch glass is
just a simple piece of glassware that can be used to hold and weigh an amount of solid.
They wobble a bit, so be gentle with them. Similarly, this is an evaporating dish. Sometimes
you may need to let a wet solid sit and dry. We can use an evaporating dish for this. They
are typically ceramic and have high edges. Now this little thing is a melting point tube.
When performing melting point determination, you need a melting point tube. These look like
little capillaries but they are in fact sealed at one end. They are very thin and small so make sure
you have an area where you can safely place them. Solid is added to the open end, and the tube
can be placed in any melting point apparatus when measuring the melting point of a compound.
In the same vein, here is an NMR tube and cap. When you need to obtain an NMR spectrum, this
is the tube we will use, and here is the cap we use. Simply make a rather concentrated
solution of the compound you’d like to run, add it to the tube with a pipette, and then
cap it. This is now ready for the spectrometer. Now let’s head over to the fume hood. We
will tend to run reactions in here, so many instruments will live inside the hood. This is
a combination hot plate and magnetic stirrer. As one would guess, this piece of equipment can
both heat and stir your reaction. One dial will control the heat, and the other will control
the rotational speed of the magnetic stir bar. The heating may need to be calibrated
as the dial may not be totally accurate. Some have a plug for an external thermometer
to be used so keep an eye out for that. As for the stirrer, a small Teflon stir bar can
be placed in the solution and the contents of the reaction flask will be mixed, like
so. The stirring can get quite aggressive, so be sure to clamp up the vessel to
stop it from possibly falling over. Another indispensable piece of equipment is the
scale, or balance. Scales are used to weigh the mass of solids accurately. Be sure to tare
the scale with any vessel you are weighing. What this means is that whatever will hold
the solid, we can place it on the balance and zero the mass, so that the measurement we take
correlates precisely with the solid that is added. Make sure to avoid pouring or scooping the
solid onto the vessel while it is on the scales, as any residual material may cause the expensive
scales to break or malfunction. Take the vessel off the scale each time you want to add or
remove solid from the vessel you are using. And that wraps up an introduction to the
equipment you are most likely to use in the chemistry laboratory. Knowing how to use this
equipment properly is the best way to stay safe while doing chemistry, in addition to becoming
familiar with any eye wash or shower stations, and appropriate disposal containers.
These will be specific to your lab, so be sure to pay attention when instructed on
how to use these by your own instructor. But with this basic information understood, let’s move
forward and start learning some simple techniques.
