The document provides guidelines for the storage and handling of various chemicals in laboratory settings, emphasizing safety measures such as proper labeling, use of fume hoods for corrosive substances, and specific protocols for handling acids and ethers. It also discusses the safe limits of chemical vapors and outlines the importance of antidotes and first aid for chemical exposure. Additional instructions include methods for heating, stirring, filtering, and calibrating laboratory equipment like pipettes and balances.

1. ANALYTICAL CHEMISTRY
(Storage and handling of Chemicals)
Dr.S.SURESH
Assistant Professor
Email:avitsureshindia@gmail.com

2. Storage and handling of chemicals
The following rules should be strictly observed in storing
and handling of chemicals.
• After using a chemical, the container should be tightly
closed and returned to its original place.
• Care should be taken to see if all the containers have the
appropriate labels stuck to them. No bottle should be left
unlabelled.
• Corrosive chemicals should be stored in corrosion-
resistant chambers.
• Some chemicals especially concentrated acids, produce
lot of fumes on exposing to the atmosphere and
therefore it is advisable to handle these inside a fume-
hood.

3. Storage and handling of chemicals
• Flammable solvents like benzene, alcohol, ether
and carbon disulphide should never be handled
without turning off burners, heaters, etc.
• Some of the organic solvents like ether, because of
their high volatility, build-up a pressure in the
containers. Such containers should be cooled in ice
and then opened.
• Flammable liquids should not be heated in an open
vessel over a free flame. They should be heated in a
flask fitted with a reflux condenser

4. Handling of acids
• Store strong acids separately and away from volatile
organic chemicals.
• Wear acid resistant chemical gloves and aprons, when
working with acids. Emergency flood showers or eye
wash foundation must be available.
• Dilute acids by stirring the concentrated acid slowly
into the water. Do not pour water in to acid.
• When using acids, make available suitable
neutralizing agents for use in the event of spills.
• Acids should be neutralized with weak bases such as
sodium carbonate or bicarbonate.

5. Handling of Ethers
• When ethers are exposed to air for long periods,
peroxides are formed. Accidentally detonation of
peroxides will lead to explosions. This danger is
more, when ether is distilled. When there is a doubt
about the presence of peroxides in ethers, these
should not be handled without check.

6. Toxic chemicals
The various chemical classes of toxic compounds
S.No Class Examples
1 Aromatic hydrocarbons
Benzene, toluene, xylene,
naphthalene, Anthracene
2 Amines
Aliphatic amines, anilines,
Napthyl amine
3 Chlorinated aliphatic hydrocarbons CHCl3, CCl4, CHCl2, CH2Cl
4 Inorganic Compounds
Compounds of the elements
Be, Cd, Co, Cr, Ni, Pb, Ti, V
etc.

7. Safe limits of vapour concentrations
• The safe limits of concentrations of chemical
vapours in the air we breathe are much smaller than
what we normally assume. For example, the
threshold concentration limit for mercury vapour is
0.1µg/cubic metre, which can be easily attained from
mercury spills on warm laboratory floors. Therefore
stringent safety rules and careful handling of
chemicals are essential for keeping the laboratory
atmospheric concentrations of chemicals below the
threshold limits.

8. Threshold limit values for some toxic vapours
S.No Substance
Threshold limit
(µg/cubic metre )
1 Acetone 2400
2 Ammonia 70
3 Carbon monoxide 110
4 Ethyl amine 45
5 Hydrogen sulphide 30
6 Mercury 0.1
7 Nitric acid 25
8 Formaldehyde 6

9. Antidotes
• An antidote is a substance which can counteract a
form of poisoning. It is prudent to assume that
every chemical used in the laboratory is a poison
and hence handle it with care.

10. Treatment of specific poisons
• If a chemical is swallowed, immediate treatment
should be given to the patient.
• Acetone: Induce vomiting and administer universal
antidote. Keep the patient awake.
• Universal antidote: This is prepared by mixing 2 parts
of pulverised charcoal, 1 parts of magnesium oxide
and 1 part of tannic acid. A few grams of this can be
added to a cup of warm water and then
administered. This universal antidote is administered
when a specific antidote is not known.

11. • Acids:
Do not induce vomiting, administer magnesium oxide, or
lime water immediately. Repeat the dose every fifteen or
twenty minutes. Administer milk or white egg in cold water.
Carbonates should not be given to the patient. Administer a
few millilitres of mineral oil four or five times every fifteen
minutes.
• Alkalis:
Do not induce vomiting, administer 5% acetic acid or vinegar.
Then administer, milk or white of egg.
• Methyl alcohol:
Induce vomiting and then administer milk or white of egg

12. First aid Technique
Organic substances on the skin:
• Wash liberally with rectified spirit, then with soap
and warm water.
Acid on clothing:
• Apply dilute ammonium hydroxide to the affected
area of the dress and then wash thoroughly with
water.
Alkali on clothing:
• Apply dilute acetic acid on the affected portion and
then wash with plenty of water

13. Heating methods
• A variety of methods for heating chemicals can be used in the
laboratory. Some of the method includes, the use of Bunsen
burner, hot plate, and heating mantle.
Heating with a Bunsen burner:
• The Bunsen burner is used routinely in the general chemistry
laboratory. Many organic chemicals are flammable, and an open
flame is an invitation to starting a laboratory fire or an explosion
of combustible vapours. Never use a Bunsen burner in the
presence of highly flammable solvents. In the organic
chemistry laboratory, the Bunsen burner provides a high-
temperature heat source (1000°C) for heating.

14. Heating with a Hot Plate
• The variable-temperature hot plate is a very versatile
heating unit. The main advantage of using a hot plate
is that it provides a flameless variable-temperature
heat from a flat surface, so no additional support is
normally required when using a flat- bottomed flask.

15. Heating with a Heating Mantle
• A heating mantle is a specialized kind of heating
device designed to be used only with round-
bottomed flasks when liquids are being heated
under reflux or are being distilled. There are
different heating mantles for each size of flask.

17. Stirring
• A mixture can be agitated with a magnetic stirrer and with a
mechanical stirrer.
Magnetic Stirrers:
• Magnetic stirring is the method of choice if an extended
period of continuous agitation is required, since it is easy to
set up the apparatus; particularly for small scale set-ups or
closed systems.

18. Mechanical Stirrers
• Larger scale reactions or viscous mixtures require
the greater power of an external motor unit turning
a stirrer blade. It is highly advantageous for the
motor to possess a variable speed control and a
typical model is shown in the diagram

19. Filtration
• There are few experiments in organic
chemistry that do not involve atleast one
filtration step. Filtration is done by allowing
the liquid to pass through a porous barrier,
such as filter paper or sintered glass,
whereby the solid remains on the barrier.

20. Gravity Filtration
• Gravity filtration is a simple technique only
requiring a filter funnel, a piece of filter paper and a
vessel, called the filter flask, usually an Erlenmeyer
flask, for collecting the filtrate. Glass funnels are
available in several sizes

21. Vacuum Filtration
• Carrying out a filtration using
vacuum is faster than using gravity
alone, but requires some
additional equipment.
• Since the technique relies on
producing a partial vacuum in the
receiving flask, a thick-walled
filter flask with a side arm, often
called a Buchner flask, must be
used.

22. Pipette
Calibration of Pipette

23. Calibration of Pipette
• The pipette is first rinsed with distilled water and the
pipette is filled with distilled water.
• The water in the pipette is then drained into a clean,
weighed stoppered weighing bottle.
• The draining should be done slowly by keeping the tip
of the pipette in contact with the side of the bottle.
• The draining from the pipette is completed when the
meniscus comes to rest slightly above the end of the
pipette tip.
• The weighing bottle is reweighed. The temperature of
the water is noted.
• The exact volume of the pipette is obtained from the
weight of the water drained using Table1

24. Calibration of pipette
• The volume and weight of water contained in the
pipette depends upon the temperature.
Volume occupied by 1.0g of water weighed
S.No Temperature (°C) Volume (ml)
1 10 1.0013
2 11 1.0014
3 12 1.0015
4 13 1.0016
5 14 1.0018

25. Burette
Calibration of Burette

26. Calibration of Burette
• The burette is filled with distilled water.
• The water level in the burette is adjusted to the
zero mark.
• The water is then drained fully into clean dry
stoppered weighed 100cm3 flask.
• Any drop adhering to the tip must be removed
by touching the neck of the flask against the tip.
• Restopper and reweigh the flask. Find out the
weight of water drained and note it carefully.
• Repeat this procedure for for every cm3 or every
5 cm3 in a50cm3 burette.

27. Calibration of Burette
• Note the temperature of the water and find out the
volume delivered at each point from the weight
using Table 1
• Volume occupied by 1.0g of water weighed
S.No Temperature (°C) Volume (ml)
1 10 1.0013
2 11 1.0014
3 12 1.0015
4 13 1.0016
5 14 1.0018

28. Calibration of standard measuring flask

29. Calibration of standard measuring flask
• The standard flask is first thoroughly cleaned and
dried.
• Deionised water is then added slowly in to the flask
through a small funnel until the mark is reached.
• When water is near the graduation mark, using a
dropping tube, water is added drop wise until the
meniscus stands on the graduation mark.
• The stopper is replaced and the flask is reweighed.
• The actual volume of the water filling the flask up to
the mark can be calculated with the help of Table 1.

30. Chemical Balance

31. Weighing process in a chemical balance
In using analytical balance usually the following sequence is
followed.
• Sit opposite the balance, so that you face the centre of the
balance.
• Remove any dust on the pans gently using a brush.
• Release the beam carefully without jerk and check that the
pointer swings equally on either side of the zero reading on
the scale. Otherwise adjust carefully to obtain this condition.
• Arrest the beam and then gently place the objects on the
centre of the left side pan and close the balance case.
• Place suitable weights on the right side pan and check for
equal oscillation. The pointer should swing through four or
five divisions beyond the mid-point of the scale. At the final
stage, rider must be used

32. Weighing process in a chemical balance
• When it is necessary to add more of solid or liquid,
this must be done outside the balance case.
• Adding and removing the weights is done with
minimum disturbance on the pan and always on the
arrested position of the beam.
• The pans must on no account be touched while the
beam is swinging.
• When the oscillation is equal, note carefully the
weight of the object correct to 0.1mg.
• Arrest the beam, return the weights to the weight
box, remove the object from the pan and clean the
pans and the floor of the balance gently with the
brush. Remember to close the balance case before
you leave the balance room.

34. Single pan balance

35. Weighing in a single pan balance
• Rotate the arrest knob to the full release position and
adjust the zero adjusting control until the illuminated scale
indicates a reading of zero.
• Arrest the balance and place the object to be weighed on
the pan. After turning the arrest knob to its partial release
position, rotate the dial controlling the heaviest likely
weight for the object until the illuminated scale changes
position.
• The removal of the correct range of weight is indicated by
the gentle movement of the illuminated scale being in view.
Inadequate or excessive removal will make the illuminated
scale disappear from the illuminated window

36. Weighing in a single pan balance
• When weights equivalent to the weight of the
object have been removed, turn the arrest knob to
its full release position and allow the balance to
achieve equilibrium.
• The weight of the object is found by taking the sum
of the weights indicated on the dials and that which
appears on the illuminated scale.
• A vernier is use in reading the scale to the nearest
tenth of a milligram.