CHEMISTRY LABORATORY APPARATUS
Period:
Duration: 40 MIN (each) Average
age of learners: 15YRS
Subject: CHEMISTRY
Class: SS ONE
Topic: CHEMISTRY LABORATORY APPARATUS
Reference materials:
(1) ESSENTIAL CHEMISTRY, TONALD PUBLISHERS, I. O ODESINA
(2) NEW SCHOOL CHEMISTRY, AFRICAN FIRST PUBLISHERS, OSEI YAW
ABABIO
(3) INTERNET
Instructional materials: BEAKER,
FLASK, PIPETTES
Entry behavior: The students have
been familiar with students with lab coat.
Behavioural objective: At
the end of the lesson the students should be able to:
i. state FIVE laboratory rules.
ii. Identify and differentiate between beaker and conical
iii. identify test tube, watch glass, crucible, graduated
cylinder, volumetric flask and pipette
iv.state uses of test tube, volumetric cylinder and pipette.
v.identify burette, forcept, spatula, Bunsen burner and balances
vi.state uses of Bunsen burner and burette
CHEMISTRY LABORATORY APPARATUS
Presentation
STEP I:
The teacher states the laboratory rules.
SAFETY RULES IN CHEMISTRY LABORATORY
v
Do not enter a laboratory without permission.
v
Never enter a prep room without permission.
v
Do not bring bags into the lab.
v
Do not play with electrical sockets, gas taps and water taps.
v
You must not touch or do anything with equipment or materials
without permission.
v
You must obey instructions from your teacher - if you are unsure
ask.
v
You must wear safety glasses when told to do so.
v
Hair, scarves, ties etc are tied back or tucked in when using
Bunsen.
v
Stand in front of your stool when using Bunsen or otherwise
instructed.
v
Behave sensibly at all times.
v
Handle bottles carefully and always replace the tops when not in
use.
v
Never eat in the laboratory. Only drink if your teacher gives you
permission.
v
Wash your hands after handling chemicals.
v
Never put broken glass in the waste bin – always use the sand
bucket.
v
Report any accident, breakage or spillage to the teacher
immediately.
v
Keep your bench clean and tidy.
STEP
II: The students chorus the safety rules in chemistry laboratory
STEP
III: The teacher explains safety equipment, beakers, conical flask and Florence
flask.
LABORATORY APPARATUS AND THEIR USE
1.
1. 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.
2. Beakers
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. However, a watch glass (discussed below) can
be used to cover the opening to prevent contamination or splashing.
3. Erlenmeyer flasks, AKA conical
flasks
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.
4. Florence flasks, AKA boiling flasks
Also 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.
Draw a well labeled diagram of
beaker and conical flask
STEP Iv: The teacher explains test
tubes, watch glasses, crucibles and funnel.
5.
5. Test tubes being lifted with tongs
from a rack
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.
6. 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.
7. Crucibles
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.
8. Funnels
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.
STEP II: The teacher explains graduated
cylinder, volumetric flasks and pipettes to the students
9.
9. 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.
10. Volumetric flasks
A volumetric flask is a round flask with a
long neck and flat bottom. It is used to measure an exact volume of liquid and
for the preparation of standard solutions. 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).
11. 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.
12. 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.
Evaluation: The teacher evaluates the lessons by asking
the following questions:-
3RD & 4th PERIOD
STEP I: The teacher revises the
previous lesson with the students.
STEP II: The teacher explains
burette, tongs and spatula
13.
13.
A burette.
These are usually attached with a clamp to a
ring stand, as shown in the picture below.
A burette 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 burette 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. Burettes are one of the
most accurate tools in the lab.
14. Ring Stands, Rings, and Clamps
The ring stand is used to suspend burette,
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.
15. Tongs and Forceps
Tongs and forceps are for grabbing things that
should not be touched by hand. Some tongs are specially made to hold beakers,
others to hold test tubes, and so on. There are also general tongs.
Forceps are used to grab small things like
solid chemicals that are broken into chunks, so they can be safely handled and
added to containers.
16. Scoopulas and
Spatulas.
Spatulas and scoopulas are for scooping solid
chemicals. They are typically used to scoop a chemical out of its original
container onto a weigh boat so that it can be weighed on a balance.
STEP III: The students draw burette, tongs and
spatula
STEP IV: The teacher explains thermometer,
Bunsen burner and balance
STEP III: The students draw thermometer,
Bunsen burner and balance
17
17. Thermometers
A 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.
18 Bunsen burner
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.
19. Balances
A balance is used to weigh chemicals. The
chemicals are always in some form of container and never placed directly on the
balance. It is important not to move a balance because they have been calibrated
for the exact position they are in. Some balances have plastic housing with
small doors to keep air currents from affecting the measurement. Close these
doors whenever the balance is in use.
Evaluation: The teacher evaluates the lessons by asking
the following questions:-
i. state FIVE laboratory rules.
ii. Identify and differentiate between beaker and conical flask
iii. identify test tube, watch glass, crucible, graduated
cylinder, volumetric flask and pipette
iv. state uses of test tube, volumetric cylinder and pipette.
V. identify burette, forcept, spatula, Bunsen burner and balances
vi. state uses of Bunsen burner and burette
ASSIGNMENT: Read about matter
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