In
most labs, you'll encounter the same basic apparatus. Here, you will
find a picture and an explanation for how to use each piece of
equipment. You will learn about:
Safety goggles and safety equipment
Beakers
Erlenmeyer flasks, AKA conical flasks
Florence flasks, AKA boiling flasks
Test tubes, tongs, and racks
Watch glasses
Crucibles
Funnels
Graduated cylinders
Volumetric flasks
Droppers
Pipettes
Burets
Ring stands, rings, and clamps
Tongs and forceps
Spatulas and scoopulas
Thermometers
Bunsen Burners
Balances
The Equipment You're Most likely To Encounter And Their Functions
Safety goggles and safety equipment
The
first and foremost rule of any laboratory is to be safe! This may seem
obvious, but people often disregard safety protocols for one reason or
another, putting themselves and those around them in danger. The best
thing you can do is to make sure you follow all safety protocols at all
times.
Safety goggles are required wear in all chemistry labs. Not wearing
them puts you in danger of eye irritation and possibly blindness in the
case of an accident. A small droplet of acid could splash out of the
container at any time. Better safe than permanently blinded!
Latex gloves should be used when there is a possibility of corrosive chemicals spilling onto your hands.
A lab apron or coat can also prevent injury in case of spills or splashes.
Never wear open-toed shoes or sandals in a lab.
BEAKER
A
beaker is a common container in most labs. It is used for mixing,
stirring, and heating chemicals. Most beakers have spouts on their rims
to aid in pouring. They also commonly have lips around their rims and
markings to measure the volume they contain, although they are not a
precise way to measure liquids. Beakers come in a wide range of sizes.
Because of the lip that runs around the rim, a lid for a beaker does
not exist. However, a watch glass (discussed below) can be used to cover
the opening to prevent contamination or splashing.
CONICAL FLASK or ERLENMEYER FLASK
Also known as a conical flask, the Erlenmeyer flask was named after
its inventor in 1861. It has a narrow neck and expands toward its base.
This allows easy mixing and swirling of the flask without too much risk
of spilling. The narrow opening also allows for the use of a rubber or
glass stopper. It can easily be clamped to a ring stand (discussed
below) as well as heated or shaken mechanically.
Once again, the marks on the side are meant primarily for estimation rather than precision.
An important safety tip here is to never heat this flask while it is
capped. This could cause a pressure build-up that could result in
explosion.
FLORENCE FLASK or BOILING FLASK
known as a boiling flask, the Florence flask has a round bottom and a
long neck. It is used to hold liquids and can be easily swirled and
heated. It can also easily be capped by rubber or glass stoppers.
Once again, safety dictates that this flask never be heated when capped. Pressure build-up and explosions can and do occur.
TEST TUBE
A test tube is a glass tube with one end open and the other end
closed. The closed end is rounded. Test tubes are used to hold small
samples. They are primarily used for qualitative assessment and
comparison. A common place to see these is the biochemistry lab. When a
large number of samples need to be tested and compared, test tubes are
used to make this easier. They are also easily capped with a rubber or
glass stopper.
They are generally held in a test tube rack specifically designed for
the purpose. If the test tubes become unsafe to touch with bare hands
(whether due to heat or another reason), test-tube tongs can be used to
move them.
Never heat a capped test tube
WATCH GLASSES
A
watch glass is just a round piece of glass that is slightly
concave/convex (think of a lens). It can hold a small amount of liquid
or solid. They can be used for evaporation purposes and also can
function as a lid for a beaker.
CRUCIBLE
A
crucible is a small clay cup made of a material that can withstand
extreme temperatures. They are used for heating substances and come with
lids.
FUNNEL
A
lab funnel is just like any other funnel except that it was designed to
be used in a laboratory setting. They can be made of plastic or glass
and can have either a short stem or a long stem, depending on what they
are needed for. There are several sizes that can be chosen from based on
the amount of liquid that needs to go through them quickly.
GRADUATED CYLINDERS
This
is a primary measuring tool for the volume of a liquid. There are
several markings up and down the length of the container with specific
increments. Graduated cylinders come in many sizes. The smaller they are
in diameter, the more specific the volume measurements will be.
When reading the volume from a graduated cylinder, you will notice
that the liquid seems to have an indentation. The liquid around the
edges will be higher than the liquid in the center, sloping down like
the sides of a trampoline when someone is standing in the middle. This
is called the meniscus. Line the lowest point of the meniscus up with
the nearest marking, keeping the cylinder level to properly read the
volume.
VOLUMETRIC FLASK
A
volumetric flask is a round flask with a long neck and flat bottom. It
is used to measure an exact volume of liquid. There is a small line on
the neck that indicates how far to fill the bottle (use the bottom of
the meniscus). They come with special caps that will not let anything in
or out.
Remember that temperature affects volume; therefore avoid using
liquids that will fluctuate in temperature (hot water that will cool,
for example).
DROPPERS
These
are small glass tubes with narrow tips on one end and a rubber bulb on
the other. They suck up liquid that can then be squeezed out in small
drops. These can be used to add an indicator to a solution about to be
titrated.
PIPETTES There are a large variety of pipettes designed to accomplish specific
goals. However, they are all for measuring an exact volume of liquid and
placing it into another container.
A buret. These are usually attached with a clamp to a ring stand, as shown in the picture below.
A
buret is a glass tube that is open at the top and comes to a narrow
pointed opening at the bottom. Right above the bottom opening is a
stopcock that can be turned to control the amount of liquid being
released. There are markings along the length of the tube that indicate
the volume of liquid present.
A buret is used for extremely accurate addition of liquid. By
adjusting the stopcock, the amount of liquid that is released can be
slowed to a drop every few seconds. Burets are one of the most accurate
tools in the lab.
Burets are set up by using a buret clamp in combination with a ring stand, discussed below.
To determine how much liquid is added, write down how much is
initially in the buret. Then when you're finished adding, write down how
much is left. Subtract the final amount from the initial amount and you
have the volume of liquid added.
Again, remember to measure from the bottom of the meniscus.
ATTACHING A BURET TO A RING STAND
RING STANDS WITH RING ATTACHEDThe
ring stand is used to suspend burets, beakers, flasks, crucibles, etc.
above other containers or, in some cases, a heat source (such as a
Bunsen burner, discussed below).
Always make sure everything is clamped to the stand tightly. When
clamping glass, be careful not to shatter the glass. Only tighten until
snug.
When using a ring on the stand, there are usually other pieces
necessary to accomplish the goal. Wire mesh is laid across the ring to
distribute evenly heat and support the beaker. A clay triangle with an
open center is used to suspend crucibles.
Make sure everything is balanced! Do not let the whole setup tip over.
THERMOMETERSA laboratory thermometer is used for measuring the temperature of
liquids. It can be made of glass or it can be a thermocouple made of
different metals. An unlit bunsen burner connected to a gas source
A
Bunsen burner is a mechanical apparatus that is connected to a
flammable gas source. There is a knob to adjust the amount of gas flow
and a rotating collar that controls airflow. These both must be adjusted
to get an ideal flame for heating purposes. The burner is lit with a
striker.
Utmost safety is required when using a Bunsen burner.
SEPARATION TECHNIQUES Basically, a mixture contains more than one substance and each constituents retains its individual properties. As a result of this we are able to separate mixtures. Thus, the techniques employed in separating mixtures make use of the physical properties of its constituents. TYPES OF SEPARATION TECHNIQUES TECHNIQUES SEPARATING MIXTURE(S) OF Sieving Solids of different sizes Separating funnel Immiscible liquids Magnetic method Magnetic solids from non-magnetic solids Decantation, Filtration, Centrifugation Insoluble solid from a liquid Chromatography Solutes from solution Distillation Solvent from its solute Fractional distillation Miscible liquids into its component parts of fractions Sieving: Sieving is in separating lumps from powdered materials i.e. Solid particles of
Atomic Theory Matter is made up of main particles known as atoms, molecules and ions. Atoms: by definition, an atom is the smallest particle of an element which can take part in a chemical reaction. Its actual existence was established in the nineteenth century when John Dalton, an English chemist, put forward a theory to describe the nature of the atom. The atom is now considered to be the basic unit of simple substances or elements. DALTON’S ATOMIC THEORY In 1808, John Dalton proposed the Atomic Theory which can be summarized as follows; · All elements are made up of small, indivisible particles called atoms. · Atoms can neither be created nor destroyed . · Atoms of the same element are alike in every aspect, and differ from atoms of all other elements. · When atoms combine with each other atoms, they do so in simple ratios. · All chemical changes result from the combination or the separation of atoms.
known as a boiling flask, the Florence flask has a round bottom and a long neck. It is used to hold liquids and can be easily swirled and heated. It can also easily be capped by rubber or glass stoppers. Once again, safety dictates that this flask never be heated when capped. Pressure build-up and explosions can and do occur.
A crucible is a small clay cup made of a material that can withstand extreme temperatures. They are used for heating substances and come with lids.
A buret. These are usually attached with a clamp to a ring stand, as shown in the picture below.
ATTACHING A BURET TO A RING STAND
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