Exercise No. 3
HANDLING AND USES OF GLASSWARES
Laboratory glassware refers to a variety of equipment, used for scientific
experiments and work, especially in agricultural research laboratories. The three most
common types of glass used in laboratory glassware are 1) soft soda-lime glass; 2) hard
borosilicate glass; and 3) pure quartz glass. Most laboratory glassware is manufactured
with borosilicate glass, which is made up of silica and boron oxide, a particularly durable
glass that can safely be used for heating of chemicals over a flame. The borosilicate
glasswares are resistance to high temperature and corrosive material and hence are
commonly used for reagent bottles. For some applications quartz glass is used due to
its ability to withstand high temperatures or its transparency in certain parts of
the electromagnetic spectrum as it made up of 99 per cent silica. In other applications,
especially some storage bottles, darkened brown or amber (actinic) glass is used to
keep out much of the UV and IR radiation, so that the effect of light on the contents is
minimized.
While working in a laboratory, you would have handled many different kinds of
glassware, each of which has specific features that make it well-suited to certain
applications. Knowing the differences between the kinds of glassware available to you
will help you to carry out experiments more efficiently. Just like borosilicate glasswares
does not use for Boron estimation. Some common glassware and their uses are given
below.
1.
BEAKER
Beakers are cylindrical containers of varied sizes,
with a small pouring lip.
Uses:
Beakers can be used for mixing and
transporting solutions, heating fluids over an open
flame, containing chemicals during a reaction and
to hold samples for later utilization.
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2.
ERLENMEYER FLASK
Erlenmeyer flasks have a short cylindrical neck
and have flat bottomed conical base, also known
as conical flask.
Uses:
Erlenmeyer flasks are similar in function to
beakers, but its conical shape help to swirl
solution without spilling and slow evaporation. In
laboratory generally used for volumetric titrations.
3.
BUCHNER FLASK
Buchner flask is almost identical to Erlenmeyer
flask, with the addition of a side-mounted pipe on
the neck of the flask, and made up of thick glass
to withstand vacuum pressure.
Uses:
Buchner flask use for vacuum filtration or
the collect the condensed liquid when system is
under negative pressure.
4.
MEASURING CYLINDER
Measuring cylinders are tall, narrow graduated
pipe type containers provided with wide base.
Uses:
Used for general purpose measuring
volume of liquid. They are not use for
measurement of liquid for quantitative analysis as
their printed graduations are generally accurate
about 1 per cent.
5.
VOLUMETRIC FLASK
Volumetric flasks have a long neck with etched
graduated
marking
to
indicate
precise
measurement of a given volume.
Uses:
Used to prepare solution of known
concentration. And also used to make precise
dilutions.
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6.
BURETTE
A burette is a graduated (0 to 50 ml) glass tube
with a rubber tube tap or stopcock on the bottom
taper / bottom end.
Uses:
Burettes are used for titration. It is also
used for precise measurement of solution in
quantitative analysis.
7.
PIPETTE
A pipette is a long glass tube, either graduated
lengthwise or fixed volume provided with bulb at
centre of the tube.
Uses:
Pipettes are used to draw precisely
measured amounts of liquid. The squeezer bulbs
are used to draw the fluid into pipette.
8.
FUNNEL
Round wide mouth conical shaped having narrow
tube at bottom end help for funneling.
Uses:
Funnels are used for pouring / funneling
liquids from one container to another or for
filtering when equipped with filter paper.
9.
SEPARATING FUNNEL
A conical shape vessel provided with stopcock at
the bottom end narrow tube.
Uses:
Separation of liquid / solution of high
density from the low density.
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10.
TEST TUBE
A test tube is a relatively slim finger like vessel with
a rounded bottom.
Uses:
Test tubes are designed to hold relatively
small quantities of chemicals and used to contain
small reactions.
In microbial / pathological studies used for
isolation of microbial colonies on solid media.
Handling of Glasswares
It is very important that glassware is used and stored properly to prevent failure
or injury during working in laboratory.
•
All glasswares should be inspect before use, scratches greatly reduces its
strength and there is possibility of breakage during working hence discarded.
•
Do not let glasswares / apparatus in contact with metal, gravel, stone, pebble
even other glassware to avoid damage.
•
Plastic stirring rods and scrapers should be used to prevent scratches and to
prolong life of the glasswares.
•
Glass should not be scribed or etched, specially important when it is to be used
for vacuum or pressure work.
•
All laboratory glassware should be clean and dry glassware immediately after
use to prevent chemical residue from congealing or hardening.
•
Glasswares joints and stopcocks will be greased for smoother application, which
will also prevent leakages and breakages during operation.
•
However, when not in use, remove and clean all stoppers, adapters and plugs to
prevent “sticking” problems.
•
If glassware or quartzware is to be heated, it must be triple rinsed in deionized or
distilled water after cleaning and dried thoroughly. This will ensure contaminates
are not burned onto glassware permanently.
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